[Intermittent] - Added pubs are not retained in a-c table

[GeetaSarvadnya]

Description

Added pubs are not retained in a-c table

Steps to Reproduce

1. Clean profile 1.1.1 beta staging env
2. Enable rewards and claim grants
3. Add GH (verified + not verified) pubs into a-c table (e.g: https://github.com/jdkuki,https://github.com/LaurenWags)
4. Wait for auto contribution to complete
5. Make sure a-c table becomes empty after the auto contribution
6. Add a GH site to a-c table (https://github.com/jdkuk - not verified)
7. Make sure it occupies 100% attention rate
8. Add 2nd GH site to a-c table (https://github.com/NejcZdovc - not verified)
9. GH pub which is added in step 6 removed from a-c table and pub which is added in step 8 remains in a-c table

Actual result:

Added pubs are not retained in a-c table

Expected result:

Added pubs should retain in a-c table

Reproduces how often:

Intermittent

Brave version (brave://version info)

Brave	1.1.1 Chromium: 78.0.3904.97 (Official Build) beta (64-bit)
Revision	021b9028c246d820be17a10e5b393ee90f41375e-refs/branch-heads/3904@{#859}
OS	Windows 10 OS Version 1803 (Build 17134.1006)

Version/Channel Information:

• Can you reproduce this issue with the current release? No
• Can you reproduce this issue with the beta channel? Yes
• Can you reproduce this issue with the dev channel? Not sure
• Can you reproduce this issue with the nightly channel? Not sure

Other Additional Information:

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

Miscellaneous Information:

cc: @brave/legacy_qa @NejcZdovc

[NejcZdovc]

are you sure that maybe contribution was not triggered?