TAC: Close Release Announcement when TAC button is clicked

[florianduros]

Checklist

• Tests written for new code (and old code if feasible).
• New or updated public/exported symbols have accurate TSDoc documentation.
• Linter and other CI checks pass.
• Sign-off given on the changes (see CONTRIBUTING.md).

Fix part of element-hq/element-web#27412

[RiotRobot]

The backport to staging failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-staging staging
# Navigate to the new working tree
cd .worktrees/backport-staging
# Create a new branch
git switch --create backport-12475-to-staging
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 6a3741b7794bc16ad75f392a44b1b07d5e50f432
# Push it to GitHub
git push --set-upstream origin backport-12475-to-staging
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-staging

Then, create a pull request where the base branch is staging and the compare/head branch is backport-12475-to-staging.