fix: cluster.metricsCollector invoked before assign when MountWebhooks

[zou8944]

Type of change:

• Bugfix
• New feature provided
• Improve performance
• Backport patches

What this PR does / why we need it:

Pre-submission checklist:

• Did you explain what problem does this PR solve? Or what new features have been added?
• Have you added corresponding test cases?
• Have you modified the corresponding document?
• Is this PR backward compatible? If it is not backward compatible, please discuss on the mailing list first

[zou8944]

the issue: #1427

[codecov-commenter]

Codecov Report

Merging #1428 (a19da39) into master (eff8ce1) will increase coverage by 0.54%.
The diff coverage is 36.90%.

❗ Current head a19da39 differs from pull request most recent head 28cad96. Consider uploading reports for the commit 28cad96 to get more accurate results

@@            Coverage Diff             @@
##           master    #1428      +/-   ##
==========================================
+ Coverage   40.89%   41.44%   +0.54%     
==========================================
  Files          78       82       +4     
  Lines        7231     7232       +1     
==========================================
+ Hits         2957     2997      +40     
+ Misses       3933     3889      -44     
- Partials      341      346       +5     

Impacted Files	Coverage Δ
pkg/api/validation/apisix_consumer.go	0.00% <ø> (ø)
pkg/api/validation/apisix_route.go	24.59% <ø> (+2.85%)	⬆️
pkg/api/validation/apisix_tls.go	0.00% <ø> (ø)
pkg/api/validation/apisix_upstream.go	0.00% <ø> (ø)
pkg/apisix/apisix.go	61.36% <ø> (ø)
pkg/apisix/resource.go	56.79% <0.00%> (-6.23%)	⬇️
pkg/config/config.go	64.13% <ø> (-2.22%)	⬇️
pkg/providers/apisix/translation/apisix_route.go	31.51% <ø> (+6.48%)	⬆️
pkg/providers/apisix/translation/translator.go	0.00% <ø> (ø)
pkg/providers/ingress/translation/annotations.go	58.82% <ø> (ø)
... and 17 more

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[tao12345666333]

Please check the lint error