EpdgSelector: timeout for DnsResolver query future

- EpdgSelector's thread sometimes gets stuck because it
never receives a response (with result, error or exception)
from native dnsresolver module.
- As a result the thread is left hanging and fwk may have to
retry setupDataCall after 60s timeout.
- Proactively throws exception on native dnsresolver timeout of 5s
for serial DNS resolution.

Bug: 228635303
Test: Live test, EpdgSelectorTests pass.
Change-Id: I682e6c7d6723ded08eb89a6b4926667fe3ac23c8
1 file changed