feat: alert on rollback when canary not ready

[rvanoo]

Implements #1816

[aryan9600]

lgtm with a couple of nits - thank you! 🎖️

[codecov-commenter]

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Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 30.19%. Comparing base (ceab3ec) to head (9a1d374).
⚠️ Report is 20 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/controller/scheduler.go	0.00%	2 Missing ⚠️
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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1817      +/-   ##
==========================================
+ Coverage   30.00%   30.19%   +0.19%     
==========================================
  Files         287      288       +1     
  Lines       18467    18535      +68     
==========================================
+ Hits         5541     5597      +56     
- Misses      12195    12203       +8     
- Partials      731      735       +4     

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[arthurchnsx]

Hello, since the PR is approved and passed all checks do you think it could be merged and shipped in the next release ?
@aryan9600