disable contextual onboarding

[SabrinaTardio]

Task/Issue URL: https://app.asana.com/0/0/1208965309086157/f

Description: We want to disable the contextual onboarding while leaving the rest of the treatment variant

Optional E2E tests:

• Run PIR E2E tests
  Check this to run the Personal Information Removal end to end tests. If updating CCF, or any PIR related code, tick this.

Steps to test this PR:

1. Run ./clean-app.sh debug
2. In MainWindowController in shouldShowOnboarding leave only line 87 and 88
3. Run the app (repeat the above steps until you get the new onboarding)
4. go through the onboarding and at the end check that no contextual dialog is present.

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Definition of Done:

• Does this PR satisfy our Definition of Done?

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[ayoy]

LGTM, but please retarget to release (and you may need to update the branch so that only this change is being merged to the release branch).