fix: translate tier add errors properly

[harshavardhana]

Description

fix: translate tier add errors properly

Motivation and Context

avoid logs such as these

Dec 08 09:55:07 play minio[4034686]: API: AddTier()
Dec 08 09:55:07 play minio[4034686]: Time: 09:55:07 UTC 12/08/2022
Dec 08 09:55:07 play minio[4034686]: DeploymentID: f2b80bd5-02a4-455d-b268-b20fb3a1d93b
Dec 08 09:55:07 play minio[4034686]: RequestID: 172EC8CFF481F70E
Dec 08 09:55:07 play minio[4034686]: RemoteHost: 127.0.0.1
Dec 08 09:55:07 play minio[4034686]: Host: 127.0.0.1:9000
Dec 08 09:55:07 play minio[4034686]: UserAgent: MinIO (linux; amd64) madmin-go/2.0.0
Dec 08 09:55:07 play minio[4034686]: Error: unsupported tier type (*errors.errorString)
Dec 08 09:55:07 play minio[4034686]:        objectLocation=cmd.auditObjectOp{Name:"config/tier-config.bin", Pool:1, Set:1, Disks:[]string{"/home/play/data1", "/home/play/data2", "/home/play/data3", "/home/play/>
Dec 08 09:55:07 play minio[4034686]:        6: internal/logger/logger.go:258:logger.LogIf()
Dec 08 09:55:07 play minio[4034686]:        5: cmd/api-errors.go:2211:cmd.toAPIErrorCode()
Dec 08 09:55:07 play minio[4034686]:        4: cmd/admin-handler-utils.go:251:cmd.toAdminAPIErrCode()
Dec 08 09:55:07 play minio[4034686]:        3: cmd/admin-handler-utils.go:238:cmd.toAdminAPIErr()
Dec 08 09:55:07 play minio[4034686]:        2: cmd/tier-handlers.go:111:cmd.adminAPIHandlers.AddTierHandler()
Dec 08 09:55:07 play minio[4034686]:        1: net/http/server.go:2109:http.HandlerFunc.ServeHTTP()

How to test this PR?

Add an invalid tier type

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Optimization (provides speedup with no functional changes)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• Fixes a regression (If yes, please add commit-id or PR # here)
• Unit tests added/updated
• Internal documentation updated
• Create a documentation update request here

[minio-trusted]

Mint Automation

Test	Result
mint-large-bucket.sh	✔️
mint-fs.sh	✔️
mint-erasure.sh	✔️
mint-dist-erasure.sh	✔️
mint-compress-encrypt-dist-erasure.sh	✔️
mint-pools.sh	✔️
Deleting image on docker hub
Deleting image locally

[krisis]

@harshavardhana the error is logged so because the error errTierTypeUnsupported wasn't checked for in toAdminAPIErr function. The underlying issue is that madmin-go should have returned madmin.ErrTierTypeUnsupported error on unmarshalling the tier config. Once we fix the madmin-go issue correctly, we can do away with these duplicate errors in cmd package.