Always report connect complete events on non-debuggable builds

Added a check for ro.debuggable system property in
FwmarkClient::shouldReportConnectComplete() and
FwmarkClient::shouldSetFwmark().
The ANDROID_NO_USE_FWMARK_CLIENT and ANDROID_FWMARK_METRICS_ONLY
environment variables will only be taken into account on
debuggable builds.

Test: manual
Bug: 29748723
Change-Id: I571ba8140412215fe92bc6e9e5e37d56ac09fb7c