Revert "Small LOH fix for Dictionary (#8024)" (#8028)

This reverts commit f174748.

Author: TIHan

src/fsharp/Optimizer.fs

@@ -3435,7 +3435,7 @@ let OptimizeImplFile (settings, ccu, tcGlobals, tcVal, importMap, optEnv, isIncr
           g=tcGlobals 
           amap=importMap
           optimizing=true
-          localInternalVals=Dictionary<Stamp, ValInfo>()
+          localInternalVals=Dictionary<Stamp, ValInfo>(10000)
           emitTailcalls=emitTailcalls
           casApplied=new Dictionary<Stamp, bool>() }
     let (optEnvNew, _, _, _ as results) = OptimizeImplFileInternal cenv optEnv isIncrementalFragment hidden mimpls