Fix #6888: Remove object freezing for XHR send patches

[cuba]

Summary of Changes

This pull request fixes #6888

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:

With shields on:

Steps 1

1. Go to the following page: https://gql.twitch.tv/149e9513-01fa-4fb0-aad4-566afd725d1b/2d206a39-8ed7-437e-a3be-862e0f06eea3/fp
2. If the page doesn't freeze, delete all cookies on that page
3. Reload the page
4. Should not freeze the tab

Steps 2

1. Reset the simulator or delete the brave application
2. Install brave and run it
3. Go to the following page: https://gql.twitch.tv/149e9513-01fa-4fb0-aad4-566afd725d1b/2d206a39-8ed7-437e-a3be-862e0f06eea3/fp
4. Should not freeze the tab

Screenshots:

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).

[kylehickinson]

Closing in favor of #6910, please re-open a new PR with code-smell specific changes if needed still :)