tests: Skip "daemon ssl files change" when SSL is disabled.

The "ovn-nbctl - daemon ssl files change" test will hang forever if SSL
is disabled. This commit fixes the issue by skipping the test if SSL is
disabled.

Signed-off-by: Mark Michelson <mmichels@redhat.com>
Acked-by: Dumitru Ceara <dceara@redhat.com>

tests/ovn-nbctl.at

@@ -2625,6 +2625,7 @@ OVN_NBCTL_TEST_STOP "/terminating with signal 15/d"
 AT_CLEANUP
 
 AT_SETUP([ovn-nbctl - daemon ssl files change])
+AT_SKIP_IF([test "$HAVE_OPENSSL" = no])
 dnl Create ovn-nb database.
 AT_CHECK([ovsdb-tool create ovn-nb.db $abs_top_srcdir/ovn-nb.ovsschema])