WifiNetworkHistory: Ignore file not found exceptions

Raise a info log message instead of logging an error when the
networkHistory.txt file is not found.

While there,
Cleanup the logs to remove the "reset to default" sentence from the logs.

BUG: 29641462
Change-Id: I572f248d0991d66ebdd118fc7ddb26680e1d7b15
TEST: Manual testing.
1 file changed
tree: e7a5ffcaa2c73f67e5f5ed6c6b35d1d240f106ec
  1. service/
  2. tests/