[test] bump Flatcar tested version to Stable

[tormath1]

What this PR does / why we need it: In this PR, we bump Flatcar channel to Stable. Akamai support (with GZIP compression support for user-data) is now available on Stable since the latest release.

Special notes for your reviewer: This is not tested yet

TODOs:

• squashed commits
• includes documentation
• adds unit tests
• adds or updates e2e tests

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 63.21%. Comparing base (161f424) to head (bbbb1ac).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/main.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #569   +/-   ##
=======================================
  Coverage   63.21%   63.21%           
=======================================
  Files          70       70           
  Lines        6090     6090           
=======================================
  Hits         3850     3850           
  Misses       1976     1976           
  Partials      264      264           

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

[tormath1]

Codecov Report

Attention: Patch coverage is 0% with 1 line in your changes missing coverage. Please review.

Project coverage is 63.21%. Comparing base (161f424) to head (bbbb1ac).
Report is 2 commits behind head on main.

Files with missing lines Patch % Lines
cmd/main.go 0.00% 1 Missing ⚠️
Additional details and impacted files

@@           Coverage Diff           @@
##             main     #569   +/-   ##
=======================================
  Coverage   63.21%   63.21%           
=======================================
  Files          70       70           
  Lines        6090     6090           
=======================================
  Hits         3850     3850           
  Misses       1976     1976           
  Partials      264      264           

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

@eljohnson92 I'm not sure what to do with this? The code coverage is not decreasing so 🤷