Explicitly set other mocking URLConnections to deflake test

The testNotifyNetwork_WithforceReevaluation() interacts with
mock fallback probe URL object, but the URLConnection
initialization for the mocking object is not applied to the
fallback one which may cause test flaky. Also apply to other
URLConnection objects.

The getHeaderField() method should also be explicitly set.

Test: atest NetworkStackTests
Fix: 302851847
Change-Id: I4feedf7b46c0cbb4b903b221b2cc540473ea8052
1 file changed