Raise threshold for detecting excessive SMS usage.

Raise threshold for detecting excessive SMS usage so that the user
is warned when an app tries to send 30 or more messages in 1 minute,
rather than 30 messages in 30 minutes. This will be much less likely
to trigger for legitimate SMS usage, while still protecting against
buggy or malicious SMS apps that try to send SMS's continuously.

Bug: 7212322
Change-Id: I97078f96fdb8584cdb3ccc830000de9a534044c0