ci: GitHub Release step fails after release:perform deletes release.properties #1338

The 3.12.1.0 release (run https://github.com/scylladb/java-driver/actions/runs/40622434506) published to Maven Central and pushed the signed tag, then failed in "Publish immutable GitHub Release" with GitHub release publication failed; values withheld.

github_release.publish() calls signing.verify_prepared(), which reads release.properties. release:perform deletes that file ([INFO] Cleaning up after release... in the maven-logs artifact), so the call raises FileNotFoundError and the catch-all hides it. The unit test stubs verify_prepared, so it never touched the file.

No real release has passed this step on either line since it landed (2c46e18 / f247a91): every other release run since then was a dry-run, which skips it. Both lines will fail the same way.

Reproduced against the real tag (HEAD 0b565b3d00, RELEASE_BASE_COMMIT=6752d1ed4d, no release.properties): verify_prepared() raises FileNotFoundError; verify_release('3.12.1.0') passes, and still raises SigningError when an unsigned commit is in range.

Fix: call signing.verify_release(version) directly — the same signature check, without re-reading the deleted file.

Second bug in the same step: gh release create refuses --notes-from-tag together with --repo (Using --notes-from-tag with --repo is not supported), and the tag message is only [maven-release-plugin] copy for tag …, unlike the generated notes of earlier releases. Fix: --generate-notes --notes-start-tag <previous four-part tag on the line>, titled by the tag.

3.12.1.0 recovery (nothing to re-release):

• GitHub Release created by hand: gh release create 3.12.1.0 --verify-tag --generate-notes --notes-start-tag 3.11.5.20 --latest=false → https://github.com/scylladb/java-driver/releases/tag/3.12.1.0
• Dispatch Docs / Publish on scylla-3.x (skipped because the release job failed)

Refs: #1322