Use Lease for leader election

[lucacome]

Proposed changes

This PR removes the need for a configmap for leader election by using a lease. It also creates a Role file to grant the necessary permissions.

[codecov]

Codecov Report

Merging #4276 (7626559) into main (9dcd4cc) will decrease coverage by 0.02%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##             main    #4276      +/-   ##
==========================================
- Coverage   52.12%   52.10%   -0.02%     
==========================================
  Files          59       59              
  Lines       16956    16958       +2     
==========================================
- Hits         8838     8836       -2     
- Misses       7821     7825       +4     
  Partials      297      297              

Files	Coverage Δ
internal/k8s/leader.go	0.00% <0.00%> (ø)

... and 1 file with indirect coverage changes

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[shaun-nx]

Did a local test of this and it worked perfectly.

Not only that, the IC acquired the lease for leader election right at the start. This normally took about 15-20 seconds after the IC started.

Great stuff Luca!

[shaun-nx]

@lucacome can you create and attach an issue for this PR as well? Thanks!