Cleaning up the payments error logs

We really don't need to see an entry in the payments error log
for every invalid or fat-fingered credit card payment attempt.
Mostly we should reserve error messages for things that we don't
expect to happen all the time, or that might indicate a programmer
error.

Change-Id: I297d7f692d80eaee454a55abb00e78770fe8a574
Merge "Cleaning up the payments error logs"