Use istio.sidecar.inject label instead of annotation

[ReToCode]

Partially knative/serving#15521

Proposed Changes

• Use istio.sidecar.inject label instead of annotation

/assign @skonto

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 78.45%. Comparing base (aabe552) to head (369cfcb).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
test/crd.go	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3096   +/-   ##
=======================================
  Coverage   78.45%   78.45%           
=======================================
  Files         191      191           
  Lines        8938     8938           
=======================================
  Hits         7012     7012           
  Misses       1663     1663           
  Partials      263      263           

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[dprotaso]

/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

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[dprotaso]

actually might need a follow up depending on the answer to this question:

knative-extensions/net-istio#1369 (comment)