correct 1p cosmetic filtering test to correctly handle ports

[pes10k]

This PR fixes the test, which previously wanted to treat the testing origin (b.com:) as 1p to the sub resource (which was b.com). This PR corrects the test to make sure the sub resource is 1p (by making it a relative resource)

Resolves brave/brave-browser#13882

Submitter Checklist:

• There is a ticket for my issue.
• Used Github auto-closing keywords in the commit message.
• Wrote a good PR/commit description
• Added appropriate labels (QA/Yes or QA/No; release-notes/include or release-notes/exclude; OS/...) to the associated issue
• Checked the PR locally: npm run test -- brave_browser_tests, npm run test -- brave_unit_tests, npm run lint, npm run gn_check, npm run tslint
• Ran git rebase master (if needed).
• Requested a security/privacy review as needed.

Reviewer Checklist:

• New files have MPL-2.0 license header.
• Adequate test coverage exists to prevent regressions
• Major classes, functions and non-trivial code blocks are well-commented
• Changes in component dependencies are properly reflected in gn
• Code follows the style guide
• Test plan is specified in PR before merging

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, 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-Exceptions-in-Brave
  • https://github.com/brave/brave-browser/wiki/QA-Guide
  • https://github.com/brave/brave-browser/wiki/P3A

Test Plan:

[simonhong]

Maybe this is not related with this PR but found while testing AdBlockServiceTest.CosmeticFilteringProtect1p on local.
When I run this test case w/o calling UpdateAdBlockInstanceWithRules("b.com##.fpsponsored\n");,
it still get success on macOS.(not release build).
I'm not sure but test should be failed w/o this rule because fpsponsored is 1p.
Curious my assumption is right or not :)

[antonok-edm]

Sorry about this 😅

[antonok-edm]

actually hang on, according to CI this is still a Windows-only failure for some reason...

[antonok-edm]

@simonhong

When I run this test case w/o calling UpdateAdBlockInstanceWithRules("b.com##.fpsponsored\n");,
it still get success on macOS.(not release build).
I'm not sure but test should be failed w/o this rule because fpsponsored is 1p.

The test here is to verify that the .fpsponsored element is still visible because of our first-party content protection rules, even though there is a matching rule in the adblock engine. So it makes sense that that would still pass.