Redirect browser requests only if the browser is enabled

[harshavardhana]

Description

Redirect browser requests only if the browser is enabled

Motivation and Context

This PR fixes an issue introduced in PR #6848, when
the browser is disabled we shouldn't re-direct the requests
returning AccessDenied.

Fixes #6907

Regression

yes introduced in #6848

How Has This Been Tested?

Accessing Minio URL from the browser when the browser is disabled.

export MINIO_BROWSER=off
minio server ~/test

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added unit tests to cover my changes.
• I have added/updated functional tests in mint. (If yes, add mint PR # here: )
• All new and existing tests passed.

[minio-ops]

Mint Automation

Test	Result
mint-tls.sh	✔️
mint-compression-xl.sh	✔️
mint-xl.sh	✔️
mint-gateway-nas.sh	✔️
mint-large-bucket.sh	✔️
mint-compression-fs.sh	✔️
mint-worm.sh	✔️
mint-fs.sh	✔️
mint-dist-xl.sh	❌ more...

6909-4bccf93/mint-dist-xl.sh.log:

Running with
SERVER_ENDPOINT:      minikube:30863
ACCESS_KEY:           minio
SECRET_KEY:           ***REDACTED***
ENABLE_HTTPS:         0
SERVER_REGION:        us-east-1
MINT_DATA_DIR:        /mint/data
MINT_MODE:            full
ENABLE_VIRTUAL_STYLE: 0

To get logs, run 'docker cp 5355c17f27d0:/mint/log /tmp/mint-logs'

(1/13) Running awscli tests ... done in 1 minutes and 43 seconds
(2/13) Running aws-sdk-go tests ... done in 0 seconds
(3/13) Running aws-sdk-java tests ... done in 6 seconds
(4/13) Running aws-sdk-php tests ... done in 48 seconds
(5/13) Running aws-sdk-ruby tests ... done in 4 seconds
(6/13) Running mc tests ... done in 34 seconds
(7/13) Running minio-dotnet tests ... FAILED in 4 minutes and 51 seconds

Unhandled Exception: System.AggregateException: One or more errors occurred. (Assert.Fail failed. ) ---> Microsoft.VisualStudio.TestTools.UnitTesting.AssertFailedException: Assert.Fail failed. 
   at Microsoft.VisualStudio.TestTools.UnitTesting.Assert.HandleFail(String assertionName, String message, Object[] parameters)
   at Minio.Functional.Tests.FunctionalTest.<>c.<ListIncompleteUpload_Test2>b__85_1(Exception ex) in /mint/run/core/minio-dotnet/FunctionalTest.cs:line 2138
   at System.Reactive.AutoDetachObserver`1.OnErrorCore(Exception exception) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Internal\AutoDetachObserver.cs:line 76
   at System.Reactive.AnonymousSafeObserver`1.OnError(Exception error) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\AnonymousSafeObserver.cs:line 62
   at System.Reactive.Linq.ObservableImpl.Throw`1._.Invoke() in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Linq\Observable\Throw.cs:line 42
   at System.Reactive.Concurrency.Scheduler.Invoke(IScheduler scheduler, Action action) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Concurrency\Scheduler.Simple.cs:line 83
   at System.Reactive.Producer`2.SubscribeRaw(IObserver`1 observer, Boolean enableSafeguard) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Internal\Producer.cs:line 127
   at System.Reactive.Linq.QueryLanguage.<>c__DisplayClass330_0`1.<Create>b__0(IObserver`1 observer) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Linq\QueryLanguage.Creation.cs:line 46
   at System.Reactive.AnonymousObservable`1.SubscribeCore(IObserver`1 observer) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\AnonymousObservable.cs:line 37
   at System.Reactive.ObservableBase`1.ScheduledSubscribe(IScheduler _, AutoDetachObserver`1 autoDetachObserver) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\ObservableBase.cs:line 82
   at System.Reactive.Concurrency.CurrentThreadScheduler.Trampoline.Run(SchedulerQueue`1 queue) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Concurrency\CurrentThreadScheduler.cs:line 126
   at System.Reactive.Concurrency.CurrentThreadScheduler.Schedule[TState](TState state, TimeSpan dueTime, Func`3 action) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\Concurrency\CurrentThreadScheduler.cs:line 94
   at System.Reactive.ObservableBase`1.Subscribe(IObserver`1 observer) in D:\a\1\s\Rx.NET\Source\src\System.Reactive\ObservableBase.cs:line 51
   at Minio.Functional.Tests.FunctionalTest.ListIncompleteUpload_Test2(MinioClient minio) in /mint/run/core/minio-dotnet/FunctionalTest.cs:line 2136
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.Wait()
   at Minio.Functional.Tests.FunctionalTest.Main(String[] args) in /mint/run/core/minio-dotnet/FunctionalTest.cs:line 241

Executed 6 out of 13 tests successfully.

[codecov]

Codecov Report

Merging #6909 into master will increase coverage by 0.26%.
The diff coverage is 66.66%.

@@            Coverage Diff             @@
##           master    #6909      +/-   ##
==========================================
+ Coverage   51.98%   52.24%   +0.26%     
==========================================
  Files         260      270      +10     
  Lines       32535    42610   +10075     
==========================================
+ Hits        16912    22261    +5349     
- Misses      13657    18385    +4728     
+ Partials     1966     1964       -2

Impacted Files	Coverage Δ
cmd/api-response.go	83.58% <66.66%> (-0.44%)	⬇️
cmd/http/conn_bug_21133.go	66.66% <0%> (-8.34%)	⬇️
main.go	50% <0%> (-7.15%)	⬇️
pkg/madmin/utils.go	16.66% <0%> (-7.15%)	⬇️
cmd/globals.go	56.52% <0%> (-7.12%)	⬇️
cmd/gateway-main.go	16.32% <0%> (-6.37%)	⬇️
cmd/auth-handler.go	67.89% <0%> (-6.01%)	⬇️
cmd/lock-rpc-server.go	30.76% <0%> (-6%)	⬇️
cmd/service.go	21.42% <0%> (-5.85%)	⬇️
cmd/server-rlimit.go	54.16% <0%> (-5.84%)	⬇️
... and 238 more

---

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[harshavardhana]

ping @balamurugana