github-secrets: use keyless

[v1v]

Use Keyless access.

Test -> https://github.com/elastic/apm-agent-php/actions/runs/9585060144

There were some failures but all of them have been addressed now:

Expand to view

Created credentials file at "/home/runner/work/apm-agent-php/apm-agent-php/gha-creds-c42c301e3f0c0e16.json"
Error: google-github-actions/auth failed with: failed to generate Google Cloud federated token for //iam.googleapis.com/projects/911195782929/locations/global/workloadIdentityPools/github/providers/repo-28ae8e252eba0f7b95257e8cb2c: {"error":"invalid_target","error_description":"The target service indicated by the \"audience\" parameters is invalid. This might either be because the pool or provider is disabled or deleted or because it doesn't exist."}

  Error: google-github-actions/upload-cloud-storage failed with: {"code":412,"message":"The type of authentication token used for this request requires that Uniform Bucket Level Access be enabled.","errors":[{"message":"The type of authentication token used for this request requires that Uniform Bucket Level Access be enabled.","domain":"global","reason":"conditionNotMet","locationType":"header","location":"If-Match"}]}

$ gsutil uniformbucketlevelaccess set on gs://apm-agent-php
Enabling Uniform bucket-level access for gs://apm-agent-php...