refactor(remove): schema cache load delay config

Remove internal schema cache load and relationship load sleep settings plus
the delay wrappers they enabled. Drop IO tests that depended on the removed
settings.

test/spec/SpecHelper.hs

@@ -159,8 +159,6 @@ baseCfg = let secret = encodeUtf8 "reallyreallyreallyreallyverysafe" in
   , configRoleSettings              = mempty
   , configRoleIsoLvl                = mempty
   , configInternalSCQuerySleep      = Nothing
-  , configInternalSCLoadSleep       = Nothing
-  , configInternalSCRelLoadSleep    = Nothing
   , configServerTimingEnabled       = True
   }