fix: preserve default values in x-goog-request-params header for artifact registry

[sofisl]

Had to run owlbot separately for artifact registry, since it was being migrated during this update.

@alexander-fenster, do these changes look right?

[conventional-commit-lint-gcf[bot]]

🤖 I detect that the PR title and the commit message differ and there's only one commit. To use the PR title for the commit history, you can use Github's automerge feature with squashing, or use automerge label. Good luck human!

-- conventional-commit-lint bot https://conventionalcommits.org/