Processing ballots is not working

[NejcZdovc]

Description

Currently you need to restart browser to finish contribution.

Steps to Reproduce

1. Enable rewards
2. Claim grant
3. Tip a verified user

Actual result:

Ballots are not processed

Expected result:

Ballots should be processed without browser restart

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:

Introduced with brave/brave-core#2654

[GeetaSarvadnya]

Verification passed on

Brave	0.68.116 Chromium: 76.0.3809.87 (Official Build) beta (64-bit)
Revision	111fe1e15d5ced26080a7dc239bcfe70f6c49aad-refs/branch-heads/3809@{#967}
OS	Windows 10 OS Version 1803 (Build 17134.523)

• Verified the test plan from Fixes ballots processing brave-core#2680 (ballots are processed after 2 mins of auto contribution)

Verified passed with

Brave	0.68.119 Chromium: 76.0.3809.87 (Official Build) beta (64-bit)
Revision	111fe1e15d5ced26080a7dc239bcfe70f6c49aad-refs/branch-heads/3809@{#967}
OS	Mac OS X

• Verified test plan from Fixes ballots processing brave-core#2680
  

Verification passed on

Brave	0.68.118 Chromium: 76.0.3809.87 (Official Build) beta (64-bit)
Revision	111fe1e15d5ced26080a7dc239bcfe70f6c49aad-refs/branch-heads/3809@{#967}
OS	Ubuntu 18.04 LTS

• Verified test plan from Fixes ballots processing brave-core#2680