no error in skaffold init if pre-existing skaffold.yaml is different from target file

[balopat]

Fixes #3554.

Should come after #3573 (it is based off of that branch).

Currently

1. If a skaffold.yaml is found anywhere in the directory, an error is thrown:
   pre-existing skaffold.yaml found (you may continue with --force)
2. This happens even when --analyze is passed in.

After this PR

If a skaffold.yaml is found anywhere in the directory, there is no error if --analyze is passed in, or the file is not the same file as the target config file for init (-f)

[codecov]

Codecov Report

Merging #3575 into master will decrease coverage by 0.01%.
The diff coverage is n/a.

Impacted Files	Coverage Δ
...affold/kubernetes/portforward/kubectl_forwarder.go	65.85% <0%> (-2.44%)	⬇️