Fix buttons wrap on about:preferences#payments (l10n)

[luixxiul]

Closes #11580

This is required for 0.19.x and 0.20.x only, like #11368

For 0.21.x and master a manual fix will be was applied to #10913

The switch label alignment has been addressed with another PR. On master it looks good.

Auditors:

Test Plan:

1. Change the lang setting to German (DE)
2. Restart the browser
3. Open about:preferences#payments
4. Make sure the buttons on the title row do not wrap

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.

Test Plan:

Reviewer Checklist:

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[luixxiul]

@zentagonist if this will not be included to 0.19.x, please close this PR. That has been manually applied to #11368 for 0.21.x. thanks!

[cezaraugusto]

++

[cezaraugusto]

0.19.x 4ae77c6
0.20.x 2a26e2c