[wpt] upgrade cookie-store tests to non-tentative

These are supported cross vendor:
https://wpt.fyi/results/cookie-store?label=experimental&label=master&aligned&q=tentative

Bug: 3534256
Change-Id: I53dd93573ce0a6b98639af9ecb160edca9973a5e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5714208
Reviewed-by: Steven Bingler <[email protected]>
Auto-Submit: Ari Chivukula <[email protected]>
Commit-Queue: Ari Chivukula <[email protected]>
Commit-Queue: Steven Bingler <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1328208}