cryptsetup: downgrade dlopen not compiled message to debug

Every other log in this function is debug level, so downgrade this too.
Otherwise compiling without libcryptsetup means sd-executor logs at
error level when starting any service, regardless of whether it is
needed or not.

Fixes https://github.com/systemd/systemd/issues/39968

Follow-up for efaf5a763d

src/shared/cryptsetup-util.c

@@ -298,7 +298,7 @@ int dlopen_cryptsetup(void) {
 
         return 1;
 #else
-        return log_error_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "cryptsetup support is not compiled in.");
+        return log_debug_errno(SYNTHETIC_ERRNO(EOPNOTSUPP), "cryptsetup support is not compiled in.");
 #endif
 }