The Onboarding Tour strings are wrongly displayed on the doorhanger

[SoftVision-CarmenFat]

[[Affected versions]:

• Release 55.0.3
• Beta 56.0
• Tab Center 1.37.0

[Affected Platforms]:

• All Windows
• All Mac

[Steps to reproduce]:

1. Open the browser.
2. Navigate to about:debugging and click "Load Temporary Add-on".
3. Select the Tab Center xpi and click on "Open".
4. Observe the Onboarding Tour.

[Expected result]:

• The text for each of the Onboarding Tour slide contains the specific title, description and related buttons.

[Actual result]:

• All the strings on the Onboarding Tour are incorrectly displayed.

[Notes]:

• Attached a screen recording of the issue:

[ericawright]

thank you, this was the specific XPI I sent.