Temporarily remove assert checks

[mschoema]

When MobilityDB is compiled in release mode, the temptype_subtype function is not defined and the following error arises when trying to CREATE EXTENSION mobilitydb_mest:

postgres=# create extension mobilitydb_mest ;
ERROR:  could not load library "/.../mobilitydb_mest.so": /.../mobilitydb_mest.so: undefined symbol: temptype_subtype

This PR temporarily removes the assert(temptype_subtype(temp->subtype)); calls to avoid this problem, while waiting for a cleaner solution.