Update DatafeedService.ts

Increase threshold of pilot difference. It occured today, that the same timestamp was present 46 times. This indicated a Datafeed fault. However, after the issue had been fixed, the difference in pilot numbers was >75, resulting in the datafeed-cache never recovering. 
Increasing the difference to 500 should solve this issue, whilst still having the check of massive discrepancies between updates. Potentially this can be removed in the future.

service/DatafeedService.ts

@@ -79,7 +79,7 @@ async function getDatafeed(): Promise<DatafeedModel | null> {
     // Also, if we queried multiple times and the same timestamp was found 6 times, then we can be pretty sure that the datafeed failed
     if (
         (datafeedStatus.data != null &&
-            (Math.abs(datafeedStatus.data.pilots.length - df.pilots.length) > 75) || df.pilots.length == 0 || same_timestamp_count > 5)
+            (Math.abs(datafeedStatus.data.pilots.length - df.pilots.length) > 500) || df.pilots.length == 0 || same_timestamp_count > 5)
     ) {
         console.error(
             '\t Update failed! Previous Pilot Count: ',