Enable gen_log for DnsResolverService and fix some style problems

1. enable gen_log in DnsResolverService
2. fix style problems in DnsResolverService
3. fix potential log_func register bug which is service is registered earlier
   than logFunc in NetdNativeService

Bug: 65862741
Test: built, flashed, booted
      system/netd/tests/runtests.sh pass

Merged-In: I80b1f7f9b054987d4f207c16ab347276abfb22c2
Merged-In: I99c6fc74ac4f95894bd874bf150cb87685d503c2
(cherry picked from commit 98b32c2c)