cleanup helm chart

[chaosi-zju]

What type of PR is this?

/kind cleanup
/kind bug

What this PR does / why we need it:

cleanup helm chart:

• set karmada-metrics-adapter image pull policy to karmadaImagePullPolicy, in order to keep the same as other components
• fix a occasional bug in post-install-job, detail refers to code comments

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[codecov-commenter]

⚠️ Please install the to ensure uploads and comments are reliably processed by Codecov.

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 28.20%. Comparing base (9928020) to head (89d3780).
Report is 4 commits behind head on master.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #5113   +/-   ##
=======================================
  Coverage   28.19%   28.20%           
=======================================
  Files         632      632           
  Lines       43571    43571           
=======================================
+ Hits        12287    12289    +2     
+ Misses      30386    30384    -2     
  Partials      898      898           

Flag	Coverage Δ
unittests	28.20% <ø> (+<0.01%)	⬆️

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

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[chaosi-zju]

@calvin0327 can you please help review this?

[RainbowMango]

/lgtm
/approve

[karmada-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: RainbowMango

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• charts/OWNERS [RainbowMango]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment