[test] Make cubicweb/test/unittest_utils.py flake8-clean

[skeleton] Set Debian distribution to "UNRELEASED" in changelog So to as to make it clear that changelog needs to be edited before the Debian package may be published.

Fix log level parameter not taken into account in cwsource log table An error in the jquery selector of the html widget controlling the log level was the cause of this bug. Closes #15772634

[config] Ignore cubicweb-pyramid in available_cubes() So that, in particular, its ccplugin.py does not get loaded (which would hide the "pyramid" command in cubicweb). Related to #14023058.

[config] Exclude "pyramid" cube when initializing application cubes Related to #14023058.

[migration] Drop cubicweb-pyramid CWProperty in 3.24.0 migration This does a partial "drop_cube('pyramid')" equivalent but only considering CWProperty. We cannot just drop the cube since we have introduced some mechanism to exclude pyramid cube from config's cubes list and that would make MigrationHelper.cmd_drop_cube() call not return "pyramid" cube. Related to #14023058.

[dataimport/test] Use minimal schema for massive import tests Drop unused stuff.

[massive store] Drop deprecated code This is not a desired part of the store API. Mapping between extid and eid should be done by the importer. This had been backported from the dataio cube, but not one seems to rely on it yet, so don't provide any backward compat.

[flake8] cubicweb/dataimport/test/test_massive_store.py is now flake8 friendly

[massive store] Drop buggy log call PGHelper has no logger, the store has.