WifiScoreReportTest: fix to pass on Android R

Convert to using a mock NetworkAgent instead
of a real one. The real NetworkAgent uses AIDL,
which causes backwards compatibility issues.

Bug: 179512200
Test: atest WifiScoreReportTest (on R & S)
Change-Id: I8883121547e655648a9a94671decb23e7ef19a27
1 file changed