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.

src/PostgREST/SchemaCache.hs

@@ -67,10 +67,9 @@ import PostgREST.SchemaCache.Table           (Column (..), ColumnMap,
 
 import qualified PostgREST.MediaType as MediaType
 
-import           Control.Arrow    ((&&&))
-import qualified Data.FuzzySet    as Fuzzy
+import           Control.Arrow ((&&&))
+import qualified Data.FuzzySet as Fuzzy
 import           Protolude
-import           System.IO.Unsafe (unsafePerformIO)
 
 type TablesFuzzyIndex = HM.HashMap Schema Fuzzy.FuzzySet
 
@@ -167,11 +166,9 @@ querySchemaCache conf@AppConfig{..} = do
   let tabsWViewsPks = addViewPrimaryKeys tabs keyDeps
       rels          = addInverseRels $ addM2MRels tabsWViewsPks $ addViewM2OAndO2ORels keyDeps m2oRels
 
-  -- Add delay in loading schema cache when internal-schema-cache-load-sleep config is set
-  return $ delayEval configInternalSCLoadSleep $ removeInternal schemas $ SchemaCache {
+  return $ removeInternal schemas $ SchemaCache {
       dbTables = tabsWViewsPks
-    -- Add delay in loading relationships when internal-schema-cache-relationship-load-sleep config is set
-    , dbRelationships = delayEval configInternalSCRelLoadSleep $ getOverrideRelationshipsMap rels cRels
+    , dbRelationships = getOverrideRelationshipsMap rels cRels
     , dbRoutines = funcs
     , dbRepresentations = reps
     , dbMediaHandlers = HM.union mHdlers initialMediaHandlers -- the custom handlers will override the initial ones
@@ -185,7 +182,6 @@ querySchemaCache conf@AppConfig{..} = do
   where
     schemas = toList configDbSchemas
     prepared = configDbPreparedStatements
-    delayEval confDelay result = maybe result (unsafePerformIO . (($> result) . (threadDelay . (1000 *) . fromIntegral))) confDelay
 
 -- | overrides detected relationships with the computed relationships and gets the RelationshipsMap
 getOverrideRelationshipsMap :: [Relationship] -> [Relationship] -> RelationshipsMap