Adjust merge tests for new string option

[phofl]

• closes #xxxx (Replace xxxx with the GitHub issue number)
• Tests added and passed if fixing a bug or adding a new feature
• All code checks passed.
• Added type annotations to new arguments/methods/functions.
• Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

[mroeschke]

Could you merge in main here once more? I think the precursor PR was merged already

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 2.2.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 9e0b6556b77b554f43067d06057dd05c6e8b8dc4

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #56445: Adjust merge tests for new string option'

4. Push to a named branch:

git push YOURFORK 2.2.x:auto-backport-of-pr-56445-on-2.2.x

5. Create a PR against branch 2.2.x, I would have named this PR:

"Backport PR #56445 on branch 2.2.x (Adjust merge tests for new string option)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

[mroeschke]

Thanks @phofl