sql: Cannot add and drop (or drop and add) index in same transaction #42844
Description
Describe the problem
It is not possible to add and drop an index (in either order) within the same transaction
To Reproduce
drop index foo cascade;
alter table t add constraint foo unique(x);
commit;
pq: index "foo" being dropped, try again later```
```root@:26257/defaultdb> begin;
alter table t add constraint foo unique(x);
drop index foo cascade;
commit;
pq: index "foo" in the middle of being added, try again later```
Setting `sql_safe_updates = FALSE` allows this behavior.