chore: modify all error contrast judgments by errors

[Fish-pro]

Signed-off-by: Fish-pro zechun.chen@daocloud.io

What this PR does / why we need it:

Filter out all error contrast judgments and modify them in the following way

➜  gatekeeper git:(master) git grep 'err ==' | grep -v ^vendor | sed 's/.*err == \([^ :),;.]\+\).*/\1/g' | grep -i Err | grep -v "err == 0" | grep -v "err == nil" | sort -u 
pkg/watch/replay.go:                                            if err == context.Canceled {

Which issue(s) this PR fixes (optional, using fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when the PR gets merged):
Fixes #

Special notes for your reviewer:

[codecov-commenter]

Codecov Report

Base: 53.32% // Head: 53.29% // Decreases project coverage by -0.02% ⚠️

Coverage data is based on head (e54f7ee) compared to base (0fc6306).
Patch coverage: 33.33% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2491      +/-   ##
==========================================
- Coverage   53.32%   53.29%   -0.03%     
==========================================
  Files         116      116              
  Lines       10270    10270              
==========================================
- Hits         5476     5473       -3     
- Misses       4373     4375       +2     
- Partials      421      422       +1     

Flag	Coverage Δ
unittests	53.29% <33.33%> (-0.03%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/watch/replay.go	78.97% <33.33%> (ø)
...onstrainttemplate/constrainttemplate_controller.go	56.45% <0.00%> (-0.72%)	⬇️

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[ritazh]

LGTM

[sozercan]

Thanks! LGTM

[maxsmythe]

LGTM