The default TCP polling alarm timer is very large(2 mins).
It's expensive in the CTS to wait for a couple alarms.
The polling alarm should be deprecated soon and replace
with callback design, so add the hidden method for testing
purpose to support the short term usage until design is
replaced with callbacks.
With the hidden method, the alarm timer will decrease to
1 second for a specified time period. The TCP sockets status
could be verified every 1 second.
Bug: 259000745
Test: m ; atest HostsideVpnTests with the follow up test
Change-Id: I99d494d3b50b2fbee73b926e92e97b1e194d43d4
e0192a7433