Fix to not cache SELECT having functions with return types are timestamptz or timetz.

Fix to not cache SELECT having functions with return types are timestamptz or timetz.

Functions with return type is timestamptz or timetz is affected by time zone setting.
Consider following scenario:

1) SELECT having such functions gets called and cache created.

2) time zone is changed.

3) same SELECT is called and the cache is used. The cache value is
correct any more because of the time zone change.

Discussion: https://www.pgpool.net/pipermail/pgpool-general/2022-July/008367.html