chore: prepare for release 1.2-rc.1

[susanshi]

Description

Chart updates for 1.2-rc.1

Checklist:

• Does the affected code have corresponding tests?
• Are the changes documented, not just with inline documentation, but also with conceptual documentation such as an overview of a new feature, or task-based documentation like a tutorial? Consider if this change should be announced on your project blog.
• Does this introduce breaking changes that would require an announcement or bumping the major version?
• Do all new files have appropriate license header?

Post Merge Requirements

• MAINTAINERS: manually trigger the "Publish Package" workflow after merging any PR that indicates Helm Chart Change

[susanshi]

looks like GK also appends rc version to the chart version. https://github.com/open-policy-agent/gatekeeper/pull/1962/files#diff-0ef82d844813f745123f7124924dc73b20918f27e1b25b7d2e146f60dc06ba2e

[binbin-li]

lgtm, thanks for adding it.