[a11y] Fix Talkback speak "Edit box, Nickname" for "Select photo" button.

In multi-user Profile info dialog, set labelFor will set the editbox
which serves as the label of the iconview represented by this info for
accessibility purposes.
But since both of views have different purposes, we should not set label
for icon.

Bug: 141455211
Test: manual
Change-Id: I6c7087fc7d2bcc75c388992c1a2b8ecc010cc279

res/layout/edit_user_info_dialog_content.xml

@@ -42,7 +42,6 @@
         android:singleLine="true"
         android:textAppearance="?android:attr/textAppearanceMedium"
         android:textAlignment="viewStart"
-        android:labelFor="@id/user_photo"
         android:inputType="text|textCapWords"
         android:selectAllOnFocus="true"
         android:hint="@string/user_nickname"