Disable wearable notifications. Ads won't look right on such a small …

[yachtcaptain23]

…screen, as

our guidelines focus on mobile and desktop, not wearables.

When we choose to implement or test this in the future,
https://developer.android.com/training/wearables/apps/creating#emulator is a great guide
for emulating Wear OS on the computer with a physical phone.

Closes brave/brave-browser#9397

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.

Test Plan:

In BraveActivity.java, fire a BraveOnboardingNotification

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.

[tmancey]

LGTM__

[SergeyZhukovsky]

++

[bbondy]

yay! @yachtcaptain23 please add a milestone on the issue and the PR (1.12.x)