Match exact host in autoplay whitelist before matching eTLD+1 (uplift to 1.4.x)

[brave-builds]

Uplift of #4741
Fixes brave/brave-browser#4621

Approved, please ensure that before merging:

• You have checked CI and the builds, lint, and tests all pass or are not related to your PR.
• You have tested your change on Nightly.
• The PR milestones match the branch they are landing to.

After you merge:

• The associated issue milestone is set to the smallest version that the changes is landed on.

[kjozwiak]

Restarting macOS due to both test-unit and test-browser failing as per the following:

• test-unit failing --> https://ci.brave.com/job/brave-browser-build-pr/job/pr4741_ap_whitelist_subdomains_1.4.x/1/execution/node/614/log/
• test-browser failing --> https://ci.brave.com/job/brave-browser-build-pr/job/pr4741_ap_whitelist_subdomains_1.4.x/1/execution/node/651/log/

[bsclifton]

macOS good to go- has a known failure captured with brave/brave-browser#6515

[kjozwiak]

Uplift into 1.4.x approved after deliberating with @brave/uplift-approvers. Only failure was related to brave/brave-browser#6515 as per #4788 (comment). However, it's a known intermittent issue that's not related to this specific PR. QA also went through the original PR on Nightly as per #4741 (comment).

Please make sure that all the correct labels are being used and the associated issue is moved into the correct milestone.