Fix #7857: Fix migration of screenshot data when there's thousands of tabs

[Brandon-T]

Summary of Changes

• Remove migration of screenshot data when migrating thousands of tabs

This pull request fixes #7857

Submitter Checklist:

• Unit Tests are updated to cover new or changed functionality
• User-facing strings use NSLocalizableString()
• New or updated UI has been tested across:
  • Light & dark mode
  • Different size classes (iPhone, landscape, iPad)
  • Different dynamic type sizes

Test Plan:

Test on dev channel only, use exact builds mentioned in the test plan, it's a very specific crash.

1. Install 1.50 (23.8.8.15)
2. 3dot menu scroll down to 'Add 1000 tabs button'. Test with 1000 or 2000 tabs
3. Upgrade to 1.51 (23.8.10.16)
4. Verify that this build loads without issues.

As an additional test you can test upgrade scenario from 1.56 to 1.57, also with 1000-2000 tabs. Keep in mind we consider capping the number of created tabs to 500 in the future

Reviewer Checklist:

• Issues include necessary QA labels:
  • QA/(Yes|No)
  • bug / enhancement
• Necessary security reviews have taken place.
• Adequate unit test coverage exists to prevent regressions.
• Adequate test plan exists for QA to validate (if applicable).
• Issue and pull request is assigned to a milestone (should happen at merge time).

[iccub]

still crashes for me :(
I submitted a crash log,. more details soon

[iccub]

It seemed to crash because the branch i work on missed Kyle's other fix for big tabs number. Cherry picked it and running the test agian

[iccub]

It works with Kyle's fix applied