remove push-image workflow

[imjasonh]

GHCR auth test passes now that it has something to krane ls: https://github.com/google/go-containerregistry/actions/runs/1814031520

[codecov-commenter]

Codecov Report

Merging #1282 (60b7621) into main (9c35968) will increase coverage by 0.03%.
The diff coverage is 89.47%.

@@            Coverage Diff             @@
##             main    #1282      +/-   ##
==========================================
+ Coverage   73.98%   74.01%   +0.03%     
==========================================
  Files         112      112              
  Lines        8364     8374      +10     
==========================================
+ Hits         6188     6198      +10     
  Misses       1573     1573              
  Partials      603      603              

Impacted Files	Coverage Δ
pkg/v1/google/keychain.go	90.00% <89.47%> (+5.00%)	⬆️

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