JitterEstimator: remove unnecessary helper functions

Move functionality to closer where the values are used instead,
as per previous CL comment.

Bug: webrtc:14151
Change-Id: I6b7ca02da197420a1f5da930ba87021e6f557444
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/275204
Commit-Queue: Rasmus Brandt <brandtr@webrtc.org>
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#38148}

modules/video_coding/timing/jitter_estimator.h

@@ -143,11 +143,6 @@ class JitterEstimator {
   Config GetConfigForTest() const;
 
  private:
-  // These functions return values that could be overriden through the config.
-  double GetNumStddevDelayOutlier() const;
-  double GetNumStddevSizeOutlier() const;
-  double GetCongestionRejectionFactor() const;
-
   // Updates the random jitter estimate, i.e. the variance of the time
   // deviations from the line given by the Kalman filter.
   //