chore(gh-action): push to master

[rahulnarla]

No description provided.

[sentry]

Bug: The workflow trigger was changed to master, but conditional logic for environment and image publishing still checks for the main branch, which will cause failures.
_{Severity: CRITICAL}

Suggested Fix

Update the hardcoded branch references from refs/heads/main to refs/heads/master in the conditional logic for the environment and publish_image steps to align with the new trigger branch.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent.
Verify if this is a real issue. If it is, propose a fix; if not, explain why it's not
valid.

Location: .github/workflows/containers.yaml#L6

Potential issue: The pull request updates the workflow to trigger on pushes to the
`master` branch instead of `main`. However, it fails to update two conditional checks
that still reference `refs/heads/main`. Specifically, the check for selecting the
`gcp-artifacts-rw` environment and the check for setting the `publish_image` flag will
both evaluate to false on pushes to `master`. This will cause the workflow to use
read-only credentials and prevent the built Docker image from being published, breaking
the CI/CD pipeline for the default branch.

_{Did we get this right? 👍 / 👎 to inform future reviews.}