`SHOW memory_spill_ratio` will always display 20 when it's the first
query in a connection (if you run this query in psql and pressed TAB
when entering the command then the implicit queries ran by the tab
completion function will be the first), the root cause is that SHOW
command will be bypassed in resgroup, so the bound resgroup will not be
assigned, and the resgroup's settings will not be loaded.

To display the proper value in this case we will also load the resgroup
settings even for bypassed queries.