chore: cleanup old barque credentials

[blva]

Proposed changes

while sorting out our release, @drichmdb mentioned that these keys are no longer used and we only need barque, so trying to cleanup unused items in our release.

Checklist

• I have signed the MongoDB CLA
• I have added tests that prove my fix is effective or that my feature works
• I have added any necessary documentation in document requirements section listed in CONTRIBUTING.md (if appropriate)
• I have addressed the @mongodb/docs-cloud-team comments (if appropriate)
• I have updated test/README.md (if an e2e test has been added)
• I have run make fmt and formatted my code

Further comments

[drichmdb]

LGTM!

[cveticm]

LGTM!
If the signing_auth_token_xx keys are stored in 1password, it would be great to remove them to keep the vault clean.

[blva]

If the signing_auth_token_xx keys are stored in 1password, it would be great to remove them to keep the vault clean.

yes, great point! I'll check where they're stored for clean up but only after some successful releases to make sure it's all good!

[drichmdb]

LGTM!