test-path: Set umask explicitly (#8616)

Running `test-path` under an umask such as 027 fails with:

  Assertion '(s.st_mode & S_IRWXO) == 0004' failed at ../src/test/test-path.c:247, function test_path_makedirectory_directorymode(). Aborting.

Looking at directory /tmp/test-path_makedirectory, it was indeed created
with mode 0740, applying the umask to the requested 0744.

Set an explicit umask for this test, to ensure reproducible results.

src/test/test-path.c

@@ -20,6 +20,8 @@
 
 #include <stdbool.h>
 #include <stdio.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 
 #include "alloc-util.h"
 #include "fd-util.h"
@@ -266,6 +268,8 @@ int main(int argc, char *argv[]) {
         const test_function_t *test = NULL;
         Manager *m = NULL;
 
+        umask(022);
+
         log_parse_environment();
         log_open();