fix: pool-coordinator cannot be rescheduled when its node fails (#1212)

[AndyEWang]

What type of PR is this?

/kind bug

What this PR does / why we need it:

when the node disconnects from all nodes except itself, pool-coordinator in this node can be rescheduled into a healthy node.

Which issue(s) this PR fixes:

Fixes #1212

Special notes for your reviewer:

/assign @rambohe-ch
/assign @Congrool

Does this PR introduce a user-facing change?

Since charts/openyurt/templates/pool-coordinator.yaml is changed, users should upgrade the running pool-coordinator.

[codecov]

Codecov Report

Merging #1218 (08d8d74) into master (c524116) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1218      +/-   ##
==========================================
- Coverage   52.35%   52.33%   -0.02%     
==========================================
  Files         106      106              
  Lines       13852    13852              
==========================================
- Hits         7252     7250       -2     
- Misses       5952     5953       +1     
- Partials      648      649       +1     

Flag	Coverage Δ
unittests	52.33% <ø> (-0.02%)	⬇️

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

Impacted Files	Coverage Δ
pkg/util/iptables/iptables.go	87.12% <0.00%> (-0.55%)	⬇️

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[openyurt-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [rambohe-ch]

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[rambohe-ch]

/lgtm

[rambohe-ch]

/backport release-v1.2

[github-actions]

Successfully created backport PR for release-v1.2:

• [Backport release-v1.2] fix: pool-coordinator cannot be rescheduled when its node fails (#1212) #1240