[1.1] chore(release): bump product_version to 1.1.1

[github-actions]

Backport of #518 for the 1.1 maintenance branch.

On main, #518 set product_version to 1.2.0 (next minor / 1.2.0-SNAPSHOT). On 1.1, the next release after shipped GA 1.1.0 is patch 1.1.1, so this PR sets product_version to 1.1.1 — not 1.2.0.

Also adds 1.1 to .backportrc.json targetBranchChoices (same backport-target change as #518).

Checklists

Pre-Review Checklist

• This PR does NOT contain credentials of any kind, such as API keys or username/passwords (double check crawler.yml.example and elasticsearch.yml.example)
• This PR has a meaningful title
• This PR links to all relevant GitHub issues that it fixes or partially addresses
• this PR has a thorough description
• Covered the changes with automated tests
• Tested the changes locally
• Added a label for each target release version (example: v0.1.0)
• Considered corresponding documentation changes
• Contributed any configuration settings changes to the configuration reference
• Ran make notice if any dependencies have been added

Changes Requiring Extra Attention

• Security-related changes (encryption, TLS, SSRF, etc)
• New external service dependencies added.

Related Pull Requests

• chore(release): bump product_version to 1.2.0 on main #518

Release Note

No user-facing runtime change. Release engineering only: the 1.1 branch is prepared for the next patch GA (1.1.1) after 1.1.0.