Rename wrong_guess_counter to failure_counter

I named the file "wrong_guess_counter" with the intention that it count
only wrong guesses, not other failures.  That would be ideal; however,
unfortunately the error codes from Weaver and Gatekeeper do not always
differentiate wrong guesses from other failures.  Therefore, the counter
does count other failures, because not rate-limiting them would make the
software rate-limiter ineffective on many devices.

Therefore, rename the file to "failure_counter".  Update code and
comments accordingly.  No functional change except the name of the file.

Note that since "failure_counter" is a less specific name anyway, this
still leaves the door open to changing exactly what types of failures
are counted in the future, including making it precisely count wrong
guesses as was my original intent.

Since this change touches the SyntheticPasswordManager class comment,
also reformat that comment to be compatible with google-java-format.

Test: atest FrameworksServicesTests:com.android.server.locksettings
Bug: 395976735
Flag: android.security.software_ratelimiter
Change-Id: I3ec9d412b70e32530acfa1352cedefed6ff29f25