Fix RayShape collision when used with a KinematicBody (Bullet Physics)

- Added code handling non-compound collision to recover_from_penetration_ray()
  which is now needed due to the optimization avoiding the use of compound
  collisions when only a single collision shape is used.
- Removed arbitrary margin applied in the collision algorithm of RayShapes
  which causes jittered movement. For lack of a better replacement and for
  lack of any explanation on why it has been introduced, it's now using the
  shape's margin property instead which is small enough to not show visible
  jitter.
- Tried to get rid of inconsistent uses of the collision margin.
- Removed hack from GodotDeepPenetrationContactResultCallback::addContactPoint
  for RayShape collision as it's no longer needed as the collision algorithm
  of RayShapes correctly calculates the contact normal for a while now.

Fixes #25227.

modules/bullet/godot_ray_world_algorithm.cpp

@@ -35,8 +35,6 @@
 
 #include <BulletDynamics/Dynamics/btDiscreteDynamicsWorld.h>
 
-#define RAY_STABILITY_MARGIN 0.1
-
 /**
 	@author AndreaCatania
 */
@@ -102,8 +100,8 @@ void GodotRayWorldAlgorithm::processCollision(const btCollisionObjectWrapper *bo
 
 		btScalar depth(ray_shape->getScaledLength() * (btResult.m_closestHitFraction - 1));
 
-		if (depth >= -RAY_STABILITY_MARGIN)
-			depth = 0;
+		if (depth >= -ray_shape->getMargin())
+			depth *= 0.5;
 
 		if (ray_shape->getSlipsOnSlope())
 			resultOut->addContactPoint(btResult.m_hitNormalWorld, btResult.m_hitPointWorld, depth);