Increase partition tooFarBlockRange from 20k to 50k

The grouping and merge threshold for dynamic contract partitions was a
fixed 20k blocks, which on sparse factories produced a large number of
partitions per registration wave. Raising it to 50k reduces the
partition count at the cost of fetching more discardable
pre-registration events per group.

https://claude.ai/code/session_01HxQeuZQ11GUAoBZdbFaDuW

Author: claude

packages/envio/src/FetchState.res

@@ -200,7 +200,7 @@ module OptimizedPartitions = {
   // We optimize for fastest data which we get in any case.
   // If the value is off, it'll only result in
   // quering the same block range multiple times
-  let tooFarBlockRange = 100_000
+  let tooFarBlockRange = 50_000
 
   let ascSortFn = (a, b) =>
     Int.compare(a.latestFetchedBlock.blockNumber, b.latestFetchedBlock.blockNumber)