containers/* treadmill: new error message on push

[edsantiago]

nightly containers/* treadmill is failing system tests:

[+0689s] not ok 224 podman push fail
....
[+0689s] # # podman push --authfile=.... --tls-verify=false quay.io/libpod/testimage:20220615 localhost:5565/badpush:1
....
[+0689s] # [ rc=125 (expected) ]
[+0689s] # #/vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv
[+0689s] # #|     FAIL: auth error on push
[+0689s] # #| expected: '.*: unauthorized: authentication required' (using expr)
[+0689s] # #|   actual: 'Getting image source signatures'
[+0689s] # #|         > 'Copying blob sha256:5f70bf18a086007016e948b04aed3b82103a36bea41755b6cddfaf10ace3c6ef'
[+0689s] # #|         > 'Copying blob sha256:d376924959cf31ee3dcd95c8079b2cc3feb1655a7182bdc638d8becfe377183c'
[+0689s] # #|         > 'Error: trying to reuse blob sha256:d376924959cf31ee3dcd95c8079b2cc3feb1655a7182bdc638d8becfe377183c at destination: checking whether a blob sha256:d376924959cf31ee3dcd95c8079b2cc3feb1655a7182bdc638d8becfe377183c exists in localhost:5565/badpush: authentication required'
[+0689s] # #\^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

local podman only (root/rootless); remote tests are passing. Something changed in some error message somewhere? Anyhow, heads-up for the next person to do vendor dance.

[vrothberg]

@mtrmac is on it in #15662

[github-actions]

A friendly reminder that this issue had no activity for 30 days.

[mtrmac]

#15662 was merged, assuming this is fine now.