[FIX] http: clear environment on checked called rollback

If the current cursor transaction was not empty when using the check
called endpoint, at the first call the cursor would be rollbacked but
the environment could still have outdated values.

This was an issue for example when selecting the route would trigger
database insert, for instance when a model was used in the route and
this model had also translatable prefetchable fields with tokens not
already present in ir.translation

opw-652045