tests: use the test helpers in more places

This is mostly cosmetic. It makes those test binaries support SYSTEMD_LOG_*
environment variables.

src/resolve/test-resolved-etc-hosts.c

@@ -10,6 +10,7 @@
 #include "log.h"
 #include "resolved-etc-hosts.h"
 #include "strv.h"
+#include "tests.h"
 #include "tmpfile-util.h"
 
 static void test_parse_etc_hosts_system(void) {
@@ -137,9 +138,7 @@ static void test_parse_file(const char *fname) {
 }
 
 int main(int argc, char **argv) {
-        log_set_max_level(LOG_DEBUG);
-        log_parse_environment();
-        log_open();
+        test_setup_logging(LOG_DEBUG);
 
         if (argc == 1) {
                 test_parse_etc_hosts_system();

src/resolve/test-resolved-packet.c

@@ -2,6 +2,7 @@
 
 #include "log.h"
 #include "resolved-dns-packet.h"
+#include "tests.h"
 
 static void test_dns_packet_new(void) {
         size_t i;
@@ -23,10 +24,7 @@ static void test_dns_packet_new(void) {
 }
 
 int main(int argc, char **argv) {
-
-        log_set_max_level(LOG_DEBUG);
-        log_parse_environment();
-        log_open();
+        test_setup_logging(LOG_DEBUG);
 
         test_dns_packet_new();