Do not call cookResources on dummy old resource registry tools.

[mauritsvanrees]

I see this when migrating from Plone 4.3 to 5.2 when I want to run a small upgrade step before doing the plone-upgrade:

$ bin/upgrade install --site minaraad --allow-outdated --upgrades 5200@Products.minaraad:default
2021-01-05 10:22:17,980 INFO    [ftw.upgrade:147][waitress-0] ______________________________________________________________________
2021-01-05 10:22:17,981 INFO    [ftw.upgrade:149][waitress-0] UPGRADE STEP Products.minaraad:default: Pre 5.2 cleanup
2021-01-05 10:22:17,982 INFO    [ftw.upgrade:156][waitress-0] Ran upgrade step Pre 5.2 cleanup for profile Products.minaraad:default
2021-01-05 10:22:17,982 INFO    [ftw.upgrade:159][waitress-0] Upgrade step duration: 1 second
2021-01-05 10:22:17,987 ERROR   [ftw.upgrade:39][waitress-0] FAILED
Traceback (most recent call last):
  File "/Users/maurits/shared-eggs/cp27m/ftw.upgrade-3.0.3-py2.7.egg/ftw/upgrade/jsonapi/plonesite.py", line 196, in _install_upgrades
    *api_ids, propose_deferrable=propose_deferrable)
  File "/Users/maurits/shared-eggs/cp27m/ftw.upgrade-3.0.3-py2.7.egg/ftw/upgrade/executioner.py", line 62, in install_upgrades_by_api_ids
    return self.install(data)
  File "/Users/maurits/shared-eggs/cp27m/ftw.upgrade-3.0.3-py2.7.egg/ftw/upgrade/executioner.py", line 54, in install
    recook_resources()
  File "/Users/maurits/shared-eggs/cp27m/ftw.upgrade-3.0.3-py2.7.egg/ftw/upgrade/resource_registries.py", line 11, in recook_resources
    registry.cookResources()
AttributeError: 'RequestContainer' object has no attribute 'cookResources'
Result: FAILURE

This is because portal_css and portal_javascripts are still there, but are dummy aliases from plone.app.upgrade.