Fixes when rewards is reset ads service should shut down

[tmancey]

Resolves brave/brave-browser#11035

Submitter Checklist:

• Submitted a ticket for my issue if one did not already exist.
• Used Github auto-closing keywords in the commit message.
• Added/updated tests for this change (for new code or code which already has tests).
• Verified that these changes build without errors on
  • Android
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that these changes pass automated tests (unit, browser, security tests) on
  • iOS
  • Linux
  • macOS
  • Windows
• Verified that all lint errors/warnings are resolved (npm run lint)
• Ran git rebase master (if needed).
• Ran git rebase -i to squash commits (if needed).
• Tagged reviewers and labelled the pull request as needed.
• Request a security/privacy review as needed.
• Add appropriate QA labels (QA/Yes or QA/No) to include the closed issue in milestone
• Public documentation has been updated as necessary. For instance:
  • https://github.com/brave/brave-browser/wiki/Deviations-from-Chromium-(features-we-disable-or-remove)
  • https://github.com/brave/brave-browser/wiki/Proxy-redirected-URLs
  • https://github.com/brave/brave-browser/wiki/Fingerprinting-Protections
  • https://github.com/brave/brave-browser/wiki/Brave%E2%80%99s-Use-of-Referral-Codes
  • https://github.com/brave/brave-browser/wiki/Custom-Headers
  • https://github.com/brave/brave-browser/wiki/Web-compatibility-issues-with-tracking-protection
  • https://github.com/brave/brave-browser/wiki/QA-Guide

Test Plan:

• Confirm Ads state is deleted when reseting Brave Rewards
• Confirm Confirmations state is deleted when reseting Brave Rewards
• Confirm Ads state is not deleted when toggling Ads on/off switch
• Confirm Ads is started and ads can be shown when disabling and then re-enabling ads

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Request a security/privacy review as needed.
• Adequate test coverage exists to prevent regressions
• Verify test plan is specified in PR before merging to source

After-merge Checklist:

• The associated issue milestone is set to the smallest version that the
  changes has landed on.
• All relevant documentation has been updated.

[emerick]

LGTM

[tmancey]

Linux and Windows failed CI, restarting.

CI failed for unrelated gn check and browser tests on other platforms

[tmancey]

CI failed for unrelated gn_check and rewards browser tests

[LaurenWags]

Discussed with @NejcZdovc and instead of testing on Nightly (which is blocked by #6248), this is being tested with PR build from https://bravesoftware.slack.com/archives/C5DT3GPCH/p1596464740328400

Brave | 1.12.106 Chromium: 84.0.4147.105 (Official Build) nightly (64-bit)
-- | --
Revision | a6b12dfad6663f13a7e16e9a42a6a4975374096b-refs/branch-heads/4147@{#943}
OS | macOS Version 10.14.6 (Build 18G3020)

• Verified test plan from description.
• Confirmed if rewards are reset, then Brave-Browser-Nightly/Default/ads_service folder is deleted.
• Confirmed if rewards are reset, then Brave-Browser-Nightly/Default/rewards_service folder is deleted.
• Confirmed re-enabling rewards creates these two folders again.
• Confirmed toggling Ads off did not remove Brave-Browser-Nightly/Default/ads_service or Brave-Browser-Nightly/Default/rewards_service folders.
• Confirmed no ads messages seen in logs when Ads were toggled off.
• Confirmed if Ads are toggled off and then the browser is restarted, ads are still off after restart.
• Confirmed Ads can be toggled on and ads messages start appearing in the logs.
• Confirmed when Ads were toggled back on the ads panel information was not lost.
• Confirmed when re-enabling Ads that ads were shown based on max per hour setting.