Brave Auto Contribute percentage values do not recalculate after removing sites

[LaurenWags]

Description

Found while testing #967 - if you remove sites from the 'Auto-Contribute' modal, the % values do not recalculate (to add up to 100%) after the sites are removed. Additionally, closing and reopening the modal does not cause the % values to recalculate so they add up to 100%. Visiting a new site adds the site to the list, but does not cause the % values to recalculate either.

Note - removing a site in Brave Payments does recalculate % values.

Steps to Reproduce

1. Clean profile with Brave Rewards enabled.
2. Visit about 8 different sites.
3. Navigate to chrome://rewards
4. Click on the link in Brave Auto Contribute container to view all sites.
5. Verify all % values add up to 100.
6. Remove 2 sites. --> % values do not update
7. Close/reopen modal. --> % values do not update
8. Close modal.
9. Open a new tab and visit a new site (different from the previous 8), wait about 10s or so on this site.
10. Go back to chrome://rewards and open modal for sites.
11. New site is listed, but if you add up the % values, they don't equal 100%

Actual result:

After removing sites % values will not add up to 100%:

Expected result:

Removing sites should change % values. Adding a new site after removing sites should also change % values so that they add up to 100% as it did in Brave Payments:

Reproduces how often:

easily

Brave version (chrome://version info)

Reproduced on Beta and Dev

Brave	0.55.10 Chromium: 70.0.3538.22 (Official Build) beta(64-bit)
Revision	ac9418ba9c3bd7f6baaffa0b055dfe147e0f8364-refs/branch-heads/3538@{#468}
OS	Mac OS X

Brave	0.56.1 Chromium: 70.0.3538.22 (Official Build) dev (64-bit)
Revision	ac9418ba9c3bd7f6baaffa0b055dfe147e0f8364-refs/branch-heads/3538@{#468}
OS	Mac OS X

Reproducible on current release:

• Does it reproduce on brave-browser dev/beta builds? yes
• Does it reproduce on browser-laptop? no

Website problems only:

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

Additional Information

cc @brave/legacy_qa @NejcZdovc

[LaurenWags]

Verified passed with

Brave	0.56.7 Chromium: 70.0.3538.77 (Official Build) beta(64-bit)
Revision	0f6ce0b0cd63a12cb4eccea3637b1bc9a29148d9-refs/branch-heads/3538@{#1039}
OS	Mac OS X

• Verified STR in description

Verification Passed on

Brave	0.56.8 Chromium: 70.0.3538.77 (Official Build) (64-bit)
Revision	0f6ce0b0cd63a12cb4eccea3637b1bc9a29148d9-refs/branch-heads/3538@{#1039}
OS	Linux

Verification Passed on

Brave	0.56.8 Chromium: 70.0.3538.77 (Official Build) (64-bit)
Revision	0f6ce0b0cd63a12cb4eccea3637b1bc9a29148d9-refs/branch-heads/3538@{#1039}
OS	Windows