Fix issues with exclusion list for Brave payments

[mrose17]

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

• Describe the issue you encountered: if a publisher site is added to the exclusion list (by accident) and then removed, it doesn't properly propagate to the browser

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

• Brave Version (revision SHA): all

• Steps to reproduce:

  1. accidentally add a news site to the exclusion list
  2. wait for a browser to get the incremental update
  3. remove the news site

• Actual result: the publisher site is not removed from the browser's copy of the exclusion list

• Expected result: the publisher site should be removed from the browser's copy of the exclusion list

• 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: none

• Any related issues: none

[bsclifton]

@mrose17 can you add test steps for this?

[bsclifton]

Also, I'm curious if you can update the title to be more "release notes" friendly (maybe something like Fix issues with exclusion list for Brave payments")