[hooks/syncschema] don't set NOT NULL on inlined relation columns The NOT NULL constraint was being added on inlined relation cardinality change while it shouldn't. We don't want this, because this forbids to add an entity without the relation set at once (it may be added later in the transaction). This patch fix synchronization hook to stop doing this. Closes #6211101

[hooks/syncschema] Turn DropColumnOp into a data operation While writing a test for a migration issue where "NOT NULL" was added to an inlined relation column, I ran into a case where the same column was deleted twice, which of course results in an error. This is because the "ecrit_par" relation used by the test is ambiguous. I've hence turned the DropColumnOp into a data operation to ensure we'll delete the column only once in such case. Related to #6211101

[server/sources] fix name error in eid_type_source_pre_131 i.e. the eid_type_source implementation used when some pre 3.13.1 database is detected. Regression from 5fbdbbe51867.