Reduce cavalry training time and increase movement speed for ranged cavalry.

The early-game cavalry rush was overly nerfed in A24 with longer train time, slower speed, and the need for stables.
This rolls that back slightly by reducing train tim from 16 to 15, and increasing the movement speed of ranged cavalry from 15 to 16.

Patch by: borg-

Differential Revision: https://code.wildfiregames.com/D3664