test: set PIPEWIRE_REMOTE to a garbage value if we didn't start a test daemon

Don't let tests connect to the system daemon which would happen if we don't
have PIPEWIRE_REMOTE set at all.

test/test-example.c

@@ -185,6 +185,8 @@ PWTEST(default_env_test)
 {
 	/* This one is set automatically */
 	pwtest_str_eq(getenv("PWTEST"), "1");
+	/* Default value */
+	pwtest_str_eq(getenv("PIPEWIRE_REMOTE"), "test-has-no-daemon");
 
 	return PWTEST_PASS;
 }