[stable20] Clear cached app config while waiting for the SCSSCache lock to return

[backportbot-nextcloud]

backport of #23478

[faily-bot]

🤖 beep boop beep 🤖

Here are the logs for the failed build:

Status of 34269: failure

acceptance-users

• tests/acceptance/features/users.feature:35

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  Scenario: disable a user                                                      # /drone/src/tests/acceptance/features/users.feature:35
    Given I act as Jane                                                         # ActorContext::iActAs()
    And I am logged in as the admin                                             # LoginPageContext::iAmLoggedInAsTheAdmin()
    And I open the User settings                                                # SettingsMenuContext::iOpenTheUserSettings()
    And I see that the list of users contains the user user0                    # UsersSettingsContext::iSeeThatTheListOfUsersContainsTheUser()
    And I open the actions menu for the user user0                              # UsersSettingsContext::iOpenTheActionsMenuOf()
      Row for user user0 in Users Settings could not be found
      Actions menu for user user0 in Users Settings could not be found (NoSuchElementException)
    And I see that the "Disable user" action in the user0 actions menu is shown # UsersSettingsContext::iSeeTheAction()
    When I click the "Disable user" action in the user0 actions menu            # UsersSettingsContext::iClickTheAction()
    Then I see that the list of users does not contains the user user0          # UsersSettingsContext::iSeeThatTheListOfUsersDoesNotContainsTheUser()
    When I open the "Disabled users" section                                    # AppNavigationContext::iOpenTheSection()
    Then I see that the list of users contains the user user0                   # UsersSettingsContext::iSeeThatTheListOfUsersContainsTheUser()