Fix NPEs in DataCallResponse

Fix NPEs in the equals method for DataCallResponse. Only check the size
for QOS bearer sessions and traffic descriptors if they are both not
null. Also fix the hash code to return the same hash regardless of list
orders.

Test: atest DataCallResponseTest
Bug: 257975797
Change-Id: I6403f71126e3e5ab300c565cf0c528268cbfe69d
Merged-In: I6403f71126e3e5ab300c565cf0c528268cbfe69d