Switch threads on for everyone

[germain-gg]

Checklist

• Tests written for new code (and old code if feasible)
• Linter and other CI checks pass
• Sign-off given on the changes (see CONTRIBUTING.md)

---

Here's what your changelog entry will look like:

✨ Features

• Switch threads on for everyone (#9879).

[dbkr]

Was the change in this file intentional? It doesn't seem related.

[germain-gg]

Yes, some code downstream is using getUserId() and this test was now failing

[t3chguy]

The PR title doesn't match what it does, it changes the default but doesn't force it

[germain-gg]

By changing the setting key and having the default to true, after this release, everyone will have threads enabled, regardless of choices they made previously.

What would you consider "force enabling threads"? And do you think that this solution is not adequate?

[t3chguy]

Force means a user cannot disable it.

But a user can

[RiotRobot]

The backport to staging failed:

The process '/usr/bin/git' failed with exit code 128

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-9879-to-staging
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 1daa34b51c6c25724c4bceb3f630d2090557bf83
# Push it to GitHub
git push --set-upstream origin backport-9879-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-9879-to-staging.