Fix bugs for ResourceDistribution

[veophi]

Signed-off-by: veophi vec.g.sun@gmail.com

Ⅰ. Describe what this PR does

1. remove forbidden namespaces "kube-system"/ "kube-public";
2. ignore "already exists" error when dry-run at webhook;
3. ignore the errors caused by "namespace-terminating";
4. change the logic when judge whether resource needs to be updated;
5. watch resource changes;
6. fix typos and etc.

[codecov-commenter]

Codecov Report

Merging #861 (545d53b) into master (0417db8) will increase coverage by 0.05%.
The diff coverage is 72.97%.

❗ Current head 545d53b differs from pull request most recent head 91b1935. Consider uploading reports for the commit 91b1935 to get more accurate results

@@            Coverage Diff             @@
##           master     #861      +/-   ##
==========================================
+ Coverage   48.23%   48.29%   +0.05%     
==========================================
  Files         118      118              
  Lines       11036    11054      +18     
==========================================
+ Hits         5323     5338      +15     
- Misses       4901     4904       +3     
  Partials      812      812              

Flag	Coverage Δ
unittests	48.29% <72.97%> (+0.05%)	⬆️

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

Impacted Files	Coverage Δ
...rcedistribution/resourcedistribution_controller.go	32.41% <42.85%> (+1.69%)	⬆️
...ting/resourcedistribution_create_update_handler.go	59.61% <75.00%> (-1.10%)	⬇️
pkg/controller/resourcedistribution/utils.go	75.35% <86.48%> (-0.06%)	⬇️
...g/webhook/resourcedistribution/validating/utils.go	75.00% <100.00%> (-3.27%)	⬇️
pkg/controller/uniteddeployment/revision.go	67.69% <0.00%> (+1.53%)	⬆️

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[furykerry]

/lgtm

[FillZpp]

/approve

[kruise-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: FillZpp

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[FillZpp]

/lgtm