Add warning for removal of multiclustercidr flag

[galal-hussein]

Proposed Changes

Remove k3s flag for multiclustercidr

Types of Changes

Since the multiclustercidr alpha support has been removed upstream, we need to remove its support from k3s

Verification

Testing

Linked Issues

• [Epic] Remove multiclusterCIDR flag #8563

User-Facing Change

Further Comments

[dereknola]

We need to remove the MulticlusterCIDR E2E test as well.

[codecov]

Codecov Report

Attention: 3 lines in your changes are missing coverage. Please review.

Comparison is base (49411e7) 46.30% compared to head (374a91c) 48.27%.
Report is 11 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8758      +/-   ##
==========================================
+ Coverage   46.30%   48.27%   +1.96%     
==========================================
  Files         148      145       -3     
  Lines       15674    15675       +1     
==========================================
+ Hits         7258     7567     +309     
+ Misses       7265     6825     -440     
- Partials     1151     1283     +132     

Flag	Coverage Δ
e2etests	46.97% <0.00%> (?)
inttests	43.54% <0.00%> (-0.24%)	⬇️
unittests	?

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
pkg/cli/server/server.go	61.92% <0.00%> (+1.79%)	⬆️

... and 59 files with indirect coverage changes

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