Reset theming in cypress test

The test in admin-settings does not reset the theming.
So when it is run before user-background, the "Default cloud background is not rendered" test fails.

This makes sure that the theming is reset before running "User default background settings"

Signed-off-by: Louis Chemineau <louis@chmn.me>

cypress/e2e/theming/user-background.cy.ts

@@ -19,15 +19,18 @@
  * along with this program. If not, see <http://www.gnu.org/licenses/>.
  *
  */
-import type { User } from '@nextcloud/cypress'
+import { User } from '@nextcloud/cypress'
 
 import { pickRandomColor, validateBodyThemingCss } from './themingUtils'
 
 const defaultPrimary = '#006aa3'
 const defaultBackground = 'kamil-porembinski-clouds.jpg'
+const admin = new User('admin', 'admin')
 
 describe('User default background settings', function() {
 	before(function() {
+		cy.resetAdminTheming()
+		cy.resetUserTheming(admin)
 		cy.createRandomUser().then((user: User) => {
 			cy.login(user)
 		})