[massive store] Store entities in temporary table as well
* on some entity type is encountered by a slave, create a dedicated table for
insertion of entities of this type by this slave, similarly to what is done
for relation - this should lower changes of conflicts in master/slaves mode ;
* delay drop of constraints and indexes to `finish` method, where copy from
temporary tables to regular table is done ;
* insertion of metadata is done by scanning temporary tables, which may be way
shorter than theier associated regular table ;
* drop drop_metadata_constraints with its constraint_dropped friend attribute,
there are no more necessary since this is done once in the `finish`.
Related to #15538303
### Requirements for tests in various cubicweb/**/test directories. ###
## shared by several test folders
cubicweb-card
docutils
Twisted < 16.0.0
webtest
## cubicweb/test
Pygments
mock
#fyzz XXX pip install fails
cubicweb-file
cubicweb-localperms
cubicweb-tag
## cubicweb/devtools/test
flake8
## cubicweb/hooks/test
psycopg2
## cubicweb/pyramid/test
pyramid >= 1.5.0
waitress >= 0.8.9
wsgicors >= 0.3
pyramid_multiauth
## cubicweb/sobject/test
cubicweb-comment