bpo-45189: Drop the "list_frozen" command from _test_embed.

[corona10]

https://bugs.python.org/issue45189

[ericsnowcurrently]

LGTM

[arhadthedev]

Since TEST_EMBED is not used anymore, line 15 (TEST_EMBED = os.path.join(SRC_DIR, 'Programs', '_testembed')) needs to be removed as well.

[corona10]

@arhadthedev Thanks!

[bedevere-bot]

⚠️⚠️⚠️ Buildbot failure ⚠️⚠️⚠️

Hi! The buildbot AMD64 Arch Linux Asan 3.x has failed when building commit 196b53e.

What do you need to do:

1. Don't panic.
2. Check the buildbot page in the devguide if you don't know what the buildbots are or how they work.
3. Go to the page of the buildbot that failed (https://buildbot.python.org/all/#builders/582/builds/834) and take a look at the build logs.
4. Check if the failure is related to this commit (196b53e) or if it is a false positive.
5. If the failure is related to this commit, please, reflect that on the issue and make a new Pull Request with a fix.

You can take a look at the buildbot page here:

https://buildbot.python.org/all/#builders/582/builds/834

Failed tests:

• test_multiprocessing_fork

Summary of the results of the build (if available):

==

Click to see traceback logs

Traceback (most recent call last):
  File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.asan/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
    ^^^^^^^^^^^^^^^^^^^^^^^^^
KeyError: '/psm_44e4f4b4'


Traceback (most recent call last):
  File "/buildbot/buildarea/3.x.pablogsal-arch-x86_64.asan/build/Lib/multiprocessing/resource_tracker.py", line 209, in main
    cache[rtype].remove(name)
    ^^^^^^^^^^^^^^^^^^^^^^^^^
KeyError: '/psm_4862a6d3'