Fix XD Pokespot encounter rates + Arbok EV Yield in Gen 6

Fix error in rates for pokespots pointed out by @Dropries here: PokeAPI#1446 (comment)

And also Arbok shows as giving 0 Attack EVs before Gen 7, I think its because its past stat value is the same as the stat that got changed, and it's marked as 0 for gen 6 and earlier.

Author: notblisy

data/v2/csv/location_area_encounter_rates.csv

@@ -3877,12 +3877,6 @@ location_area_id,encounter_method_id,version_id,rate
 1206,1,7,10
 1206,1,8,10
 1206,1,9,10
-1270,53,20,50
-1270,53,20,35
-1270,53,20,15
-1294,53,20,50
-1294,53,20,35
-1294,53,20,15
-1295,53,20,50
-1295,53,20,35
-1295,53,20,15
+1270,53,20,90
+1294,53,20,90
+1295,53,20,90

data/v2/csv/pokemon_stats_past.csv

@@ -186,7 +186,7 @@ pokemon_id,generation_id,stat_id,base_stat,effort
 542,5,5,70,0
 545,5,2,90,0
 553,5,3,70,0
-24,6,2,85,0
+24,6,2,85,2
 51,6,2,80,0
 10037,6,5,95,3
 83,6,2,65,1