[Network Connection] Correct canceling dialog behavior

Use setCancelable() rather than setCanceledOnTouchOutside() for better
code smell and consisting with general not canceling behavior.
The back key and touching outside will not cancel this dialog for better
UX.

Bug: 128877712
Test: atest NetworkRequestDialogFragmentTest
Change-Id: I19bc5637a7307610e34db15d54c1d80d5b7e379b
1 file changed