tests: don't run couple of tests related to extensions loading with chg

The couple of files test extensions loading and debugging that. It sets
`devel.debug.extensions` to True to do that.
Either we have to restart chg if this config is set or just don't run these
tests on chg. I tried the first way by adding the config option to chgserver.py
list of config subsections but that does not seem to work.

tests/test-bad-extension.t

@@ -1,3 +1,4 b''
+#require no-chg
   $ filterlog () {
   >   sed -e 's!^[0-9/]* [0-9:]* ([0-9]*)>!YYYY/MM/DD HH:MM:SS (PID)>!'
   > }

tests/test-extension-timing.t

@@ -1,3 +1,5 b''
+#require no-chg
+
 Test basic extension support
 
   $ cat > foobar.py <<EOF