metrics: count connection failures after watchdog trigger

Sometimes wifi would experience several more connection failures before
finally being able to connect after a watchdog restart trigger. Count
these failures to get a better understanding of how watchdog is
performing.

Bug: 75001353
Test: compile, unit test

Change-Id: Ibec913c0b2aadfb1aa2390966f4bfd8fff5a2cca
4 files changed