Fix exclamation icon for bugreport disclaimer should be vertically

aligned with content icons and change layout design.

1. To adjust icon and text layout to align with item_doc_list
content layout.
2. Moving the Dismiss button to be below the disclaimer rather than
next and allow the text to span the entire width of the screen.

Change-Id: If88ef993f99eb851dbf2e43959879fe911815835
Fix: 123734953
Test: atest DocumentsUITests