lint: Remove useless clickable attribute from some layout roots

Signed-off-by: Álvaro Brey <alvaro.brey@nextcloud.com>

app/src/main/res/layout/contacts_preference.xml

@@ -22,7 +22,6 @@
     android:id="@+id/drawer_layout"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:clickable="true"
     android:fitsSystemWindows="true">
 
     <!-- The main content view -->

app/src/main/res/layout/files.xml

@@ -19,11 +19,9 @@
 <androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
-
     android:id="@+id/drawer_layout"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
-    android:clickable="true"
     android:fitsSystemWindows="true">
 
     <androidx.coordinatorlayout.widget.CoordinatorLayout

app/src/main/res/layout/preview_image_activity.xml

@@ -20,8 +20,7 @@
 <androidx.drawerlayout.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:id="@+id/drawer_layout"
     android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    android:clickable="true" >
+    android:layout_height="match_parent">
 
     <com.owncloud.android.ui.components.CustomViewPager
         android:id="@+id/fragmentPager"