[release-1.15] Ensure ContainerHealthy condition is set back to True

[knative-prow-robot]

This is an automated cherry-pick of #15503

A revision is now set to ContainerHealthy=True when it has ready replicas

[dprotaso]

/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dprotaso, knative-prow-robot

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [dprotaso]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[codecov]

Codecov Report

Attention: Patch coverage is 80.64516% with 6 lines in your changes missing coverage. Please review.

Project coverage is 83.62%. Comparing base (cd671a9) to head (b536806).
Report is 2 commits behind head on release-1.15.

Files with missing lines	Patch %	Lines
pkg/testing/functional.go	62.50%	5 Missing and 1 partial ⚠️

Additional details and impacted files

@@               Coverage Diff                @@
##           release-1.15   #15713      +/-   ##
================================================
- Coverage         83.63%   83.62%   -0.01%     
================================================
  Files               219      219              
  Lines             17410    17438      +28     
================================================
+ Hits              14560    14582      +22     
- Misses             2484     2488       +4     
- Partials            366      368       +2     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[dprotaso]

blocked on - #15714

[skonto]

/test upgrade-tests