Update expanded view drop target width

Fixes: 404916122
Flag: com.android.wm.shell.enable_bubble_to_fullscreen
Test: manual
       - enable bubble to fullscreen flag
       - create bubble
       - expand bubble bar and drag bubble icon
       - observe expanded view drop target

Change-Id: I4a49df829b7f519e76a1f96eb1d56486e920388c