Fixes claim for existing wallets

[NejcZdovc]

Resolves brave/brave-browser#11144

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)
• 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:

• enable rewards
• restore wallet with some ad grants
• connect KYC wallet
• make sure that funds are transferred to uphold

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.

[emerick]

LGTM

[NejcZdovc]

CI failed on s3 upload for Windows, all good

[NejcZdovc]

Windows CI failed on known things, all good

[LaurenWags]

Verified passed with

Brave	1.15.6 Chromium: 85.0.4183.78 (Official Build) nightly (64-bit)
Revision	720ec01a54ea94d2d8b7a1d273e0fa89722fb11b-refs/branch-heads/4183@{#1603}
OS	macOS Version 10.14.6 (Build 18G3020)

• Verified test plan from Fixes claim for existing wallets #6384 and Removes anonymous address from external wallet flow #6401

• Clean profile with above build, enabled Rewards. Restored a wallet with an Ad grant waiting. Claimed Ad grant.

Connected KYC'd Uphold wallet. Confirmed seeing the below in my logs:

[ REQUEST ]
> URL: https://grant.rewards.bravesoftware.com/v3/wallet/uphold/redacted/claim
> Method: UrlMethod::POST
> Content: ...

[ RESPONSE - OnRequest ]
> Url: https://grant.rewards.bravesoftware.com/v3/wallet/uphold/redacted/claim
> Result: Success
> HTTP Code: 200
> Body: null

[ REQUEST ]
> URL: https://grant.rewards.bravesoftware.com/v1/suggestions/claim
> Method: UrlMethod::POST
> Content: ...

[ RESPONSE - OnRequest ]
> Url: https://grant.rewards.bravesoftware.com/v1/suggestions/claim
> Result: Success
> HTTP Code: 200
> Body: 

Confirmed ad grant BAT moved to Uphold: