Refs #31055 -- Added --database option to the check management command.

This avoids enabling the ``database`` checks unless they are explicitly
requested and allows to disable on a per-alias basis which is required
when only creating a subset of the test databases.

This also removes unnecessary BaseCommand._run_checks() hook.

docs/ref/checks.txt

@@ -79,7 +79,8 @@ Django's system checks are organized using the following tags:
 * ``database``: Checks database-related configuration issues. Database checks
   are not run by default because they do more than static code analysis as
   regular checks do. They are only run by the :djadmin:`migrate` command or if
-  you specify the ``database`` tag when calling the :djadmin:`check` command.
+  you specify configured database aliases using the ``--database`` option when
+  calling the :djadmin:`check` command.
 * ``models``: Checks of model, field, and manager definitions.
 * ``security``: Checks security related configuration.
 * ``signals``: Checks on signal declarations and handler registrations.
@@ -90,6 +91,11 @@ Django's system checks are organized using the following tags:
 
 Some checks may be registered with multiple tags.
 
+.. versionchanged:: 3.1
+
+    The ``database`` checks are now run only for database aliases specified
+    using the :option:`check --database` option.
+
 Core system checks
 ==================
 

docs/ref/django-admin.txt

@@ -106,6 +106,16 @@ For example, to perform only models and compatibility checks, run::
 
     django-admin check --tag models --tag compatibility
 
+.. django-admin-option:: --database DATABASE
+
+.. versionadded:: 3.1
+
+Specifies the database to run checks requiring database access::
+
+    django-admin check --database default --database other
+
+By default, these checks will not be run.
+
 .. django-admin-option:: --list-tags
 
 Lists all available tags.