delete configmap when yurtstaticset is deleting

[JameKeal]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line:
/kind bug
/kind documentation
/kind enhancement
/kind good-first-issue
/kind feature
/kind question
/kind design
/sig ai
/sig iot
/sig network
/sig storage

/kind feature

What this PR does / why we need it:

When yurtStaticSet is delete, the configmap which is created by it is still exist, and it will always be there.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

/assign @rambohe-ch

Does this PR introduce a user-facing change?

other Note

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In response to this:

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line:
/kind bug
/kind documentation
/kind enhancement
/kind good-first-issue
/kind feature
/kind question
/kind design
/sig ai
/sig iot
/sig network
/sig storage

/kind feature

What this PR does / why we need it:

When yurtStaticSet is delete, the configmap which is created by it is still exist, and it will always be there.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

/assign @rambohe-ch

Does this PR introduce a user-facing change?

other Note

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[sonarcloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
0 Code Smells

No Coverage information
0.4% Duplication

[codecov]

Codecov Report

Merging #1640 (08b7781) into master (237fe8f) will decrease coverage by 0.01%.
The diff coverage is 45.00%.

@@            Coverage Diff             @@
##           master    #1640      +/-   ##
==========================================
- Coverage   50.93%   50.93%   -0.01%     
==========================================
  Files         137      137              
  Lines       16029    16047      +18     
==========================================
+ Hits         8164     8173       +9     
- Misses       7126     7134       +8     
- Partials      739      740       +1     

Flag	Coverage Δ
unittests	50.93% <45.00%> (-0.01%)	⬇️

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

Files Changed	Coverage Δ
...ntroller/yurtstaticset/yurtstaticset_controller.go	42.15% <45.00%> (+0.46%)	⬆️

[openyurt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JameKeal, rambohe-ch

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• OWNERS [rambohe-ch]

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[rambohe-ch]

/lgtm