[gameplay-a24] Lower the repeat rate of spear cavalry

Lower repeat rate of spear cavalry so it does not look like attacking in slow motion and lower attack damage as well to compensate speeding up attack.

Differential Revision: https://code.wildfiregames.com/D1365
Patch by: @temple
Reviewed by: @wraitii, @Angen
Agreed by: @ValihrAnt, @Lionkanzen
Comments by: @badosu