Regenerate iamcredentials client

[yoshi-automation]

This PR was generated using Autosynth. 🌈

Here's the log from Synthtool:

synthtool > Executing /tmpfs/src/git/autosynth/working_repo/google-cloud-clients/google-cloud-iamcredentials/synth.py.
synthtool > Ensuring dependencies.
synthtool > Pulling artman image.
latest: Pulling from googleapis/artman
Digest: sha256:75bc07ef34a1de9895c18af54dc503ed3b3f3b52e85062e3360a979d2a0741e7
Status: Image is up to date for googleapis/artman:latest
synthtool > Cloning googleapis.
synthtool > Running generator for google/iam/credentials/artman_iamcredentials_v1.yaml.
synthtool > Generated code into /home/kbuilder/.cache/synthtool/googleapis/artman-genfiles/java.
synthtool > Running java formatter on 10 files
synthtool > Running java formatter on 1 files
synthtool > Running java formatter on 23 files
synthtool > Cleaned up 0 temporary directories.
synthtool > Wrote metadata to synth.metadata.

[sduskis]

There are backwards incompatible changes in this PR. Is that ok?

[sduskis]

@andreamlin, it looks like we need to restore format* methods here.

[andreamlin]

@sduskis Yes thanks for FYI! I was wondering what other clients would need this backwards-supporting change.

[andreamlin]

@sduskis This should be fixed if we run synthtool again (updated artman to remove the bug that had removed those functions).