Unblinded tokens not contributed correctly when not enough funds

[NejcZdovc]

Description

Steps to Reproduce

1. Enable rewards
2. Claim grant (20 BAT)
3. Connect KYC uphold
4. Set AC to 50 BAT and add verified publishers to AC table
5. Wait for AC to be triggered

Actual result:

50 is taken from Uphold account

Expected result:

20 BAT from grant and 30 BAT from Uphold

Reproduces how often:

Brave version (brave://version info)

Version/Channel Information:

• Can you reproduce this issue with the current release?
• Can you reproduce this issue with the beta channel?
• Can you reproduce this issue with the dev channel?
• Can you reproduce this issue with the nightly channel?

Other Additional Information:

• Does the issue resolve itself when disabling Brave Shields?
• Does the issue resolve itself when disabling Brave Rewards?
• Is the issue reproducible on the latest version of Chrome?

Miscellaneous Information:

[LaurenWags]

Verified passed with

Brave	1.7.79 Chromium: 80.0.3987.149 (Official Build) dev (64-bit)
Revision	5f4eb224680e5d7dca88504586e9fd951840cac6-refs/branch-heads/3987_137@{#16}
OS	macOS Version 10.14.6 (Build 18G3020)

• Verified test plan from Fixes contribution that is split brave-core#5050. Confirmed that when a mix of UGP and Uphold BAT are available, the UGP BAT is used first, then the remainder of the Auto Contribute is pulled from Uphold BAT.

• Also verified the 3 additional scenarios listed in Fixes contribution that is split brave-core#5050 (comment):
  1. Confirmed that if only Uphold BAT is available (KYC'd wallet), auto contribute worked as expected
  2. Confirmed that if only UGP BAT is available (anon wallet, no KYC'd uphold account connected), auto contribute works as expected.
  3. Confirmed that if only BAT from a restored wallet (user funded) is available, auto contribute works as expected.

Verification passed on

Brave	1.7.82 Chromium: 80.0.3987.162 (Official Build) dev (64-bit)
Revision	f2c5dd6138153bb0658091205bd1a1717f16081a-refs/branch-heads/3987@{#1034}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

• Verified test plan from Fixes contribution that is split brave-core#5050. Confirmed that when a mix of UGP and Uphold BAT are available, the UGP BAT is used first, then the remainder of the Auto Contribute is pulled from Uphold BAT.
  
  
  
  

• Also verified the 3 additional scenarios listed in Fixes contribution that is split brave-core#5050 (comment):

  1. Confirmed that if only Uphold BAT is available (KYC'd wallet), auto contribute worked as expected
  2. Confirmed that if only UGP BAT is available (anon wallet, no KYC'd uphold account connected), auto contribute works as expected.
  3. Confirmed that if only BAT from a restored wallet (user funded) is available, auto contribute works as expected.

Verification passed on

Brave	1.7.86 Chromium: 80.0.3987.163 (Official Build) (64-bit)
Revision	e7fbe071abe9328cdce4ffedac9822435fbd3656-refs/branch-heads/3987@{#1037}
OS	Ubuntu 18.04 LTS

• Verified test plan from Fixes contribution that is split brave-core#5050. Confirmed that when a mix of UGP and Uphold BAT are available, the UGP BAT is used first, then the remainder of the Auto Contribute is pulled from Uphold BAT.
  Contributed in 2 batches. First of grant. Then from wallet.
  Wallet: