Remove fork-specific GitHub Actions workflows

[Copilot]

Four fork-specific GitHub Actions workflow files were inadvertently included in this PR branch. The upstream repository uses Jenkins for CI, not GitHub Actions, and these workflows cause mergeable_state instability.

Changes

• Removed .github/workflows/codacy.yml (Codacy security scanning)
• Removed .github/workflows/maven.yml (Maven build workflow)
• Removed .github/workflows/rebase-upstream.yml (Fork rebase automation)
• Removed .github/workflows/sync-upstream.yml (Fork sync automation)

The remaining workflow files (codeql.yml, pr-checks.yml, rebase.yml, unit-tests.yml, updateRelease.yml, version-increments.yml) are preserved as they exist in upstream.

Original prompt

Remove fork-specific GitHub Actions workflow files

The branch copilot/fix-string-index-out-of-bounds in carstenartur/eclipse.jdt.ui contains 4 fork-specific GitHub Actions workflow files that should NOT be part of the upstream PR (eclipse-jdt#2778). These files don't exist in the upstream repository eclipse-jdt/eclipse.jdt.ui and are causing CI issues.

Files to DELETE:

1. .github/workflows/codacy.yml - Codacy Security Scan workflow (fork-specific)
2. .github/workflows/maven.yml - Java CI with Maven workflow (fork-specific, upstream uses Jenkins)
3. .github/workflows/rebase-upstream.yml - Rebase Upstream helper workflow (fork-specific)
4. .github/workflows/sync-upstream.yml - Sync Fork with Upstream workflow (fork-specific)

Why:

• The upstream project eclipse-jdt/eclipse.jdt.ui uses Jenkins for CI, not GitHub Actions
• These workflow files were accidentally included in the PR branch from the fork
• They cause the PR's mergeable_state to be "unstable" because the workflows fail or are inappropriate for the upstream repo

Action:

Simply delete all 4 files listed above. Do not modify any other files.

This pull request was created from Copilot chat.

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