perf: remove redundant stopwatch start call in completion logic

Author: textGamex

src/Main/Completion.fs

@@ -357,7 +357,6 @@ let completion
         // logInfo (sprintf "completion prefix %A %A" prefixSoFar (items |> List.map (fun x -> x.label)))
 
         let stopwatch = System.Diagnostics.Stopwatch.StartNew()
-        stopwatch.Start()
         let position = PosHelper.fromZ p.position.line p.position.character // |> (fun p -> Pos.fromZ)
 
         let filetext =