Hiding dashboard cards: remove prompts from site settings

[kean]

Related issue: #20296

Changes

• Remove prompts from site settings
• Remove a notice when disabling prompts

Cards visibility is now controlled using a new Personalize Home Tab screen added in #20369 that replaced the item in Site Settings

To test

• Enable "Personalize Home Tab" screen and open Dashboard
• Open the Prompts card context menu and select "Turn off prompts"
• Verify that the card got removed but not notice (snackbar) was shown
• Open site settings
• Verify that the "Prompts" row is not there

Regression Notes

1. Potential unintended areas of impact. n/a (changes only affect what's in the description)
2. What I did to test those areas of impact (or what existing automated tests I relied on). Manual testing
3. What automated tests I added (or what prevented me from doing so). n/a

PR submission checklist:

• I have completed the Regression Notes.
• I have considered adding unit tests for my changes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

[momo-ozawa]

Works as described!

[momo-ozawa]

@kean I kicked off a CI build - if it's green all good to merge 😄