updatecli-bump-vm-images.yml improvements

[michel-laterman]

#8035 has added fips bk images, these should get automatically updated in a similar manner as the non-fips images.

We may also want to use spec.files instead of spec.file to target both .buildkite/bk.integration.pipeline.yml and .buildkite/bk.integration-fips.pipeline.yml if possible