Fix sync workflow merge identity handling

[Copilot]

Target branch

• This PR creates, updates, or deletes Dataverse data and targets release-candidate.
• This PR is read-only and targets main.

Use the base selector on the pull request page before opening the PR. Promote the complete release candidate with a separate release-candidate to main pull request.

• Problem

  • The sync job in Promote main to release candidate failed while updating the promotion branch.
  • git merge --no-edit ran without a configured committer identity, then the error path attempted git merge --abort even when no merge state existed.

• Workflow change

  • Configure a local Git identity before merging on automation/main-to-release-candidate.
  • Guard git merge --abort behind a MERGE_HEAD check so the conflict path is safe when merge creation never started.

• Versioning

  • Bump DynamicsActivitiesPackage.csproj version to 1.8.94.
  • Update VersionComment to reflect the workflow fix.

• Relevant snippet

  git config user.name "github-actions[bot]"
  git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
  
  if git rev-parse -q --verify MERGE_HEAD >/dev/null; then
    git merge --abort
  fi