Furnace minecart is counter productive and its speed doesn't scale with minecartMaxSpeed

This is specifically about its behaviour with "Minecart Improvements" experiment turned on.

Even with the default speed you will notice that the furnace minecart push speed is slower than what a minecart can achieve on it's own. This can especially be seen at high minecartMaxSpeed values because the push speed stays painfully slow.

Reproduction Steps

• Set minecartMaxSpeed to 1000
• Build a powered rail track
• Place a cart and a furnace cart behind it
• Power the furnace cart

Observed Results

• The pushed minecart moves much slower than had it not been pushed
  high speed example.mp4
  default example.mp4

Expected Results

• The pushed minecart would move just as fast if not faster.