Improve wallet recovery algorithm

[mrose17]

Test Plan

1. about:preferences#payments, 'Advanced Settings..., 'Backup your Wallet', ' Save recovery file...', save as brave_wallet_recovery.txt`
2. get a vanilla browser install and turn on the ledger -- this creates a new wallet (with a new wallet address)
3. about:preferences#payments, 'Advanced Settings..., 'Recovery your Wallet', ' Import recovery keys', select brave_wallet_recovery.txt`
4. verify that value of properties.wallet.address does not change after step 3

Original issue description

• Did you search for similar issues before submitting this one? yes

• Describe the issue you encountered: current wallet recovery algorithm results in a change of bitcoin address. it shouldn't.

• Platform (Win7, 8, 10? macOS? Linux distro?): all

• Brave Version (revision SHA): 0.13.4 and prior

• Steps to reproduce:

  1. about:preferences#payments, 'Advanced Settings..., 'Backup your Wallet', ' Save recovery file...', save as brave_wallet_recovery.txt`
  2. get a vanilla browser install and turn on the ledger -- this creates a new wallet (with a new wallet address)
  3. about:preferences#payments, 'Advanced Settings..., 'Recovery your Wallet', ' Import recovery keys', select brave_wallet_recovery.txt`

• Actual result: look at ledger-state.json ... the new wallet address is still there with the balance of the old wallet transferred

• Expected result: the desired result is for the old wallet address remain in ledger-state.json

• Will the steps above reproduce in a fresh profile? If not what other info can be added? yes

• Is this an issue in the currently released version? yes

• Can this issue be consistently reproduced? yes

• Extra QA steps: none

• Screenshot if needed: n/a

• Any related issues: n/a