Shaking removes stuns faster (#4019)

# About the pull request

Doubles the speed at which shaking removes stuns.
Semi-related to #4017 Hope
that's not atomizing too much.

# Explain why it's good for the game

There's no reason to require this much clickspamming - a crowd of people
LMB'ing someone feels excessive. Teamwork good and it should feel good
to help others, currently feels like a chore particularly in cases of
facehugging.
Shouldn't affect balance much unless im forgetting some effect - other
than being facehugged - applying extremely long durations.

# Testing Photographs and Procedure
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<summary>Screenshots & Videos</summary>

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# Changelog
:cl:
balance: Shaking people up shortens stun durations by 6 instead of 3.
/:cl:

code/modules/mob/living/carbon/carbon.dm

@@ -279,9 +279,9 @@
 			playsound(loc, 'sound/weapons/thudswoosh.ogg', 25, 1, 5)
 		return
 
-	adjust_effect(-3, PARALYZE)
-	adjust_effect(-3, STUN)
-	adjust_effect(-3, WEAKEN)
+	adjust_effect(-6, PARALYZE)
+	adjust_effect(-6, STUN)
+	adjust_effect(-6, WEAKEN)
 
 	playsound(loc, 'sound/weapons/thudswoosh.ogg', 25, 1, 5)
 

code/modules/mob/living/carbon/human/human_attackhand.dm

@@ -227,9 +227,9 @@
 			playsound(src.loc, 'sound/weapons/thudswoosh.ogg', 25, 1, 5)
 		return
 
-	adjust_effect(-3, PARALYZE)
-	adjust_effect(-3, STUN)
-	adjust_effect(-3, WEAKEN)
+	adjust_effect(-6, PARALYZE)
+	adjust_effect(-6, STUN)
+	adjust_effect(-6, WEAKEN)
 
 	playsound(loc, 'sound/weapons/thudswoosh.ogg', 25, 1, 7)