fix(comments): Don't return mentions in markdown code (by default)

[nickvergessen]

• Companion to fix(chat): Don't mention in markdown code spreed#17355
• The above PR already takes care of not rendering the mentions when showing the message, but notifications are still done atm
• I made the option opt-out, as most known consumers of comments have markdown comments

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI
  • The regex of preg_replace was AI assisted

[nickvergessen]

The change in this line was from $this->getMessage() to $message, it is otherwise unchanged.

[nickvergessen]

/backport to stable33

[backportbot]

The backport to stable33 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable33
git pull origin stable33

# Create the new backport branch
git checkout -b backport/58974/stable33

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts, resolve them
git cherry-pick 11959a13

# Push the cherry pick commit to the remote repository and open a pull request
git push origin backport/58974/stable33

Error: Failed to push branch backport/58974/stable33: remote: Invalid username or token. Password authentication is not supported for Git operations.
fatal: Authentication failed for 'https://github.com/nextcloud/server.git/'

---

Learn more about backports at https://docs.nextcloud.com/server/stable/go.php?to=developer-backports.

[SystemKeeper]

To keep in mind: This does not work for non-closed backticks, which should be auto-closed according to the specs.

[Antreesy]

which should be auto-closed according to the specs.

Right, vue-library also includes a check for ``` or end-of-line to define a fenced code block (but not the inline code, iirc)