Promote dns resolution failure message to INFO

src/core/ext/resolver/dns/native/dns_resolver.c

@@ -189,7 +189,7 @@ static void dns_on_resolved(grpc_exec_ctx *exec_ctx, void *arg,
     gpr_timespec next_try = gpr_backoff_step(&r->backoff_state, now);
     gpr_timespec timeout = gpr_time_sub(next_try, now);
     const char *msg = grpc_error_string(error);
-    gpr_log(GPR_DEBUG, "dns resolution failed: %s", msg);
+    gpr_log(GPR_INFO, "dns resolution failed (will retry): %s", msg);
     grpc_error_free_string(msg);
     GPR_ASSERT(!r->have_retry_timer);
     r->have_retry_timer = true;