[release/v2.30.x] Add Maven Central release recovery mode

[trask]

Adds an opt-in recover_maven_central mode to the release workflow so a failed Central deployment can be rebuilt and uploaded without recreating outputs that were already published.

Recovery mode:

• verifies that the GitHub release already exists
• refuses to run if the javaagent artifact is already available from Maven Central
• rebuilds the main Maven Central bundle without uploading it
• verifies byte-for-byte that the rebuilt javaagent matches the existing GitHub release attachment
• uploads the already-verified bundle without regenerating it
• skips Gradle plugin publication, SBOM attachment, attestation, and GitHub release creation
• preserves the release outputs so the normal post-release updates can complete

This is intended to recover the failed 2.30.0 Central deployment after the duplicate publication coordinates were fixed in #19298.

Validation:

• actionlint .github/workflows/release.yml
• Rebuilt javaagent SHA-256: 9d6bc2ad8dd8fb7f730984988e57b8ac0a82d81c7b3b8ae795378718733a509d
• Existing GitHub release javaagent SHA-256: 9d6bc2ad8dd8fb7f730984988e57b8ac0a82d81c7b3b8ae795378718733a509d
• Direct byte comparison: identical

[opentelemetry-pr-dashboard]

Pull request dashboard status

Status last refreshed: 2026-07-22 22:11:31 UTC.

• Status: Merged.

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[Copilot]

Pull request overview

Adds an opt-in Maven Central recovery path for existing releases.

Changes:

• Validates recovery eligibility and artifact identity.
• Rebuilds and uploads only the Central bundle.
• Skips already-completed release publication steps.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.