Removes PIA

[NejcZdovc]

Resolves #14763

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).
• 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. (Ask a Brave employee to help if you cannot access this document.)

Test Plan:

• make sure that PIA is not referenced any more
  
• run browser with LEDGER_VERBOSE and make sure that requests don't go through PIA

Reviewer Checklist:

• Request a security/privacy review as needed if one was not already requested.

Tests

• Adequate test coverage exists to prevent regressions
• Tests should be independent and work correctly when run individually or as a suite ref
• New files have MPL2 license header

[ryanml]

Does useProxy here still serve a purpose? https://github.com/brave/browser-laptop/pull/14774/files#diff-3cdfdb124f718787d584e9e2b82fcedcR1638

[ryanml]

One comment left, else looks good to me.

Not critical for this PR but we can probably go ahead and remove the use of useProxy in the bat-client at some point if this was the only purpose it served.

[NejcZdovc]

@ryanml yeah we can remove it in bat-client as well

[ryanml]

lgtm 👍

[diracdeltas]

@NejcZdovc is there anything in bat-client that uses PIA? (if so we should get rid of that too)

[NejcZdovc]

@diracdeltas no we don't use any reference to PIA in bat-client

[NejcZdovc]

master c07fe93
0.24 3258025
0.23 a38be75