[server] Make internal sessions not reset 'safe'-ness on first commit
Increment the ctx_count when disabling integrity hooks so the next
commit/rollback doesn't reset our transaction and magically turn us into
a safe session.
Closes #3168027
usr/lib/PY_VERSION/*-packages/cubicweb/entities/
usr/lib/PY_VERSION/*-packages/cubicweb/ext/
usr/share/cubicweb/cubes/
usr/lib/PY_VERSION/*-packages/cubicweb/*.py