Rename popover anchor positioning tests back to .tentative

[chromium-wpt-export-bot]

These use non-standard APIs, mostly the anchor attribute but
also some anchor positioning itself. As such, they should be
.tentative.

Bug: 1309178
Change-Id: Ief9c1f6375bc234b929b9301980d4be51de0b9c2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5026613
Commit-Queue: Mason Freed <masonf@chromium.org>
Auto-Submit: Mason Freed <masonf@chromium.org>
Reviewed-by: Di Zhang <dizhangg@chromium.org>
Commit-Queue: Di Zhang <dizhangg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1223830}

[wpt-pr-bot]

The review process for this patch is being conducted in the Chromium project.

[jonathan-j-lee]

Looks like wpt-firefox-nightly-results-without-changes failed transiently with:

 0:10.07 INFO Downloading test prefs from https://hg.mozilla.org/mozilla-central/archive/tip.zip/testing/profiles/
mem avail: 14781 of 15806 MiB (93 %), swap free:    0 of    0 MiB ( 0 %)
mem avail: 14798 of 15806 MiB (93 %), swap free:    0 of    0 MiB ( 0 %)
Traceback (most recent call last):
  File "./wpt", line 10, in <module>
    wpt.main()
  File "/home/test/web-platform-tests/tools/wpt/wpt.py", line 233, in main
    rv = script(*args, **kwargs)
  File "/home/test/web-platform-tests/tools/wpt/run.py", line 1012, in run
    setup_cls, wptrunner_kwargs = setup_wptrunner(venv, **kwargs)
  File "/home/test/web-platform-tests/tools/wpt/run.py", line 984, in setup_wptrunner
    setup_cls.setup(kwargs)
  File "/home/test/web-platform-tests/tools/wpt/run.py", line 249, in setup
    self.setup_kwargs(kwargs)
  File "/home/test/web-platform-tests/tools/wpt/run.py", line 321, in setup_kwargs
    prefs_root = self.browser.install_prefs(kwargs["binary"],
  File "/home/test/web-platform-tests/tools/wpt/browser.py", line 433, in install_prefs
    unzip(get(url).raw, dest=extract_dir)
  File "/home/test/web-platform-tests/tools/wpt/utils.py", line 106, in get
    resp.raise_for_status()
  File "/home/test/web-platform-tests/_venv3/lib/python3.8/site-packages/requests/models.py", line 1021, in raise_for_status
    raise HTTPError(http_error_msg, response=self)
requests.exceptions.HTTPError: 500 Server Error: Internal Server Error for url: https://hg.mozilla.org/mozilla-central/archive/tip.zip/testing/profiles/
[taskcluster 2023-11-13 21:02:46.151Z] === Task Finished ===
[taskcluster 2023-11-13 21:02:46.815Z] Unsuccessful task run with exit code: 1 completed in 185.284 seconds