Clean up Netd and libnetd_resolv for resolver related commands

1. remove all resolver related commands in netd
2. remove unused API in libnetd_resolv

Bug: 126141549
Test: built, flashed, booted
      system/netd/tests/runtests.sh pass

Change-Id: I35ac8f241eebd6284a6a685ef86cd77a1fce4388
diff --git a/resolv/DnsResolver.cpp b/resolv/DnsResolver.cpp
index 822f860..4b39902 100644
--- a/resolv/DnsResolver.cpp
+++ b/resolv/DnsResolver.cpp
@@ -44,7 +44,7 @@
 
 bool verifyCallbacks() {
     return gResNetdCallbacks.check_calling_permission && gResNetdCallbacks.get_network_context &&
-           gResNetdCallbacks.get_dns64_prefix;
+           gResNetdCallbacks.log;
 }
 
 }  // namespace