Remove main switch

[NejcZdovc]

Resolves brave/brave-browser#11467

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Android
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that these changes pass automated tests (unit, browser, security tests) on
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that all lint errors/warnings are resolved (npm run lint, npm run gn_check)
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone
• Public documentation has been updated as necessary. For instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-compatibility-issues-with-tracking-protection
  • https://github.com/brave/brave-browser/wiki/QA-Guide

Test Plan:

plan 1:

• clean profile
• open panel
• make sure that there is no join rewards
• open rewards page
• make sure that there is no join rewards

plan 2:

• clean profile
• open panel
• claim grant
• make sure that it works correctly

plan 3:

• claim grant
• send a tip
• make sure that tip is send correctly

plan 4:

• switch to master branch
• join rewards
• enable ads and ac
• disable rewards
• switch to this branch
• start browser
• make sure that ads and ac are off

plan 5:

• clean profile
• open Task manager
• make sure that there is no rewards extension, ledger or ads process

plan 6:

• clean profile
• connect to Uphold
• make sure that you can connect successfully

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[NejcZdovc]

PR is not complete yet, just running CI

[emerick]

LGTM

[tmancey]

LGTM