Retry binding sockets in DNSResponder if errno is EADDRNOTAVAIL

Tests fail in DNSResponder::startServer() when DNSResponder is binding
the socket while the address is still being set up. This change provides
a simple fix to address this problem because the tests are unaware of
onInterfaceAddressUpdated.

Below is a real failure log:

// device log
04-22 00:29:07.854  root   802   802 I netd    : interfaceAddAddress("testtun10002", "2001:db8:2::202", 128) <1.51ms>
04-22 00:29:07.855  root  6745  6745 E DNSResponder: failed to bind UDP 2001:db8:2::202:53: Cannot assign requested address

// dumpsys netd
04-22 00:29:07.857 onInterfaceAddressUpdated(2001:db8:2::202/128, testtun10002, 128, 0) (0.04ms)

Bug: 186181084
Bug: 175269391
Test: run ResolverMultinetworkTest.GetAddrInfo_AI_ADDRCONFIG 100 times
Change-Id: I8e8824c9056bd298e0e689adfbc720abaa45fcd4