Removes legacy code from BTC times

[NejcZdovc]

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.)

Resolves #12727

Auditors:

Test Plan:

• start brave (clean profile)
• enable ledger
• set amount to 15
• restart brave and make sure that 15 is still selected
• set amount to 20
• restart brave and make sure that 20 is still selected

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

[bsclifton]

++

[bsclifton]

master 6dece0e
0.21.x 6fdf594
0.20.x 7ce5158

[codecov-io]

Codecov Report

Merging #12810 into master will decrease coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master   #12810      +/-   ##
==========================================
- Coverage   56.11%    56.1%   -0.01%     
==========================================
  Files         279      279              
  Lines       27314    27306       -8     
  Branches     4445     4441       -4     
==========================================
- Hits        15326    15320       -6     
+ Misses      11988    11986       -2

Flag	Coverage Δ
#unittest	56.1% <100%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
app/browser/api/ledger.js	55.52% <100%> (+0.37%)	⬆️
js/stores/appStoreRenderer.js	91.17% <0%> (-8.83%)	⬇️
app/renderer/components/reduxComponent.js	84.61% <0%> (-6.16%)	⬇️
js/stores/windowStore.js	27.25% <0%> (-0.31%)	⬇️