Fix #17569, #17570 - Fix disconnect state for Gemini when wallet linking fails

[jumde]

Resolves brave/brave-browser#17569
Resolves brave/brave-browser#17570

Submitter Checklist:

• I confirm that no security/privacy review is needed, or that I have requested one
• There is a ticket for my issue
• Used Github auto-closing keywords in the PR description above
• Wrote a good PR/commit description
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• Ran git rebase master (if needed)

Reviewer Checklist:

• A security review is not needed, or a link to one is included in the PR description
• New files have MPL-2.0 license header
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

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, 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-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

1. Enable Gemini flags
2. Enable Brave Rewards
3. Verify with Gemini using account A
4. Disconnect rewards
5. Verify the status shows Verify Wallet
6. Verify with Gemini using account B
7. On verification an error should be displayed
8. Wallet status should show Verify Wallet

[emerick]

LGTM

[LaurenWags]

Verified using:

Brave	1.30.43 Chromium: 93.0.4577.51 (Official Build) nightly (x86_64)
Revision	762d21050e2da59930c784c09b134d0b0b148188-refs/branch-heads/4577@{#915}
OS	macOS Version 11.5.2 (Build 20G95)

Verified test plan from #9817 (comment)
Verified STR from brave/brave-browser#17569
Verified STR from brave/brave-browser#17570

Confirmed an error message is shown. Note, error text is generic and not descriptive of the problem. Logged brave/brave-browser#17661. This does not reproduce for Uphold but does reproduce for bitFlyer (brave/brave-browser#17592):

Confirmed UI returns to pre-link state. It does not show "Disconnected" UI or a balance. "Verify wallet" is shown and no balance is displayed: