Moved a test case that caused deprecation warnings.

`cache.tests.TestEtagWithAdmin` loaded views from the `admin_views` test
package. This is problematic because when the `cache` test package is
run in isolation, `admin_views` isn't in INSTALLED_APPS, and therefore
loading its models isn't allowed since the app loading refactor.
Fixed #20609 -- Added instructions for using AnonymousUser with RequestFactory.
Fixed #23685 -- Made call_command skip checks by default

Thanks Loic Bistuer for the report/review and Tim Graham for the
review.
Revert "Fixed #23650 -- Prevented migrate from calling checks 3 times"

This reverts commit 8d6e1afe0be0570253a508f43e2ef89ae640984e.
call_command now always set skip_checks to True (tested in
user_commands).
Removed redundant skip_checks option for call_command
Fixed #23692 -- Removed alpha/beta/rc release notes.
Fixed #23668 -- Changed make_aware() and make_naive() to use the current timezone by default

Thanks Aymeric Augustin for review.
Fixed #23629 -- Allowed autodetector to detect changes in Meta.db_table.

Thanks Naddiseo for reporting.
Clarify that HTTP Accept-Language header is case-insensitive.
Fixed #23679 -- Fixed null introspection for char/text fields

Thanks Paul Dejean for the report.
Fixed #20221 -- Allowed some functions that use mark_safe() to result in SafeText.

Thanks Baptiste Mispelon for the report.
Fixed #23688 -- Updated cached_property to preserve docstring of original function
Fix SettingsCustomLoggingTest on Windows when path contains \u
Fixed #21740 -- Allowed test client data to be an empty string

This fixes a regression introduced by 2a31d00933.
Thanks tony-zhu for the report.
Fixed firstof docs error introduced in 1ea44a; refs #17906.
Fixed #23396 -- Ensured ValueQuerySets are not checked by check_related_objects.
Fixed #23695 -- Made condition decorator work for HEAD requests without ETag.
Fixed #23107 -- Made runserver output respect --no-color.

This commit reverts 67d7da5fb9498b811f0168f5df2308ad4743027f.

The previous fix changed the environment globally, which meant
that any call to `call_command(no_color=True)` prevented further
`call_command` with color.

This fix still relies on the environment because it's currently the only
way to reach WSGIRequestHandler, but it's now limited to the `runserver`
command. This seems an acceptable compromise considering `runserver` runs
indefinitely.

Thanks Tim Graham for the review.
Fixed #23583 -- More selectively ignored static/media roots

Fixed a regression introduced by 28efafa24c.
Thanks Michal Čihař for the report and initial patch, and
Collin Anderson and Tim Graham for the reviews.
Removed unneeded override_system_checks

Refs #23685.