refine test TestIpfwdEnableDisableStatusForwarding and some minor changes on test

1. fix flaky test for TestIpfwdEnableDisableStatusForwarding
2. fix time unit error in binder_test, set retry default
   interval as 50ms
3. refine naming in binder_test

Bug: 128533612
Test: built, flashed, booted
      system/netd/tests/runtests.sh pass

Change-Id: Ia03d0c30b49cdd233b627cce8bd2f3f05548798e
7 files changed