Update purging limits

[rbayliss]

Cloudflare's API supports up to 30,000 cache tag purges in a day (I think).

This is a bit unclear from Cloudflare's documentation, but they state that:

• Cache-Tag purging has a lower rate limit of up to 2,000 purge API calls in every 24 hour period. You may purge up to 30 tags in one API call. source
• Cache-Tag and host purging each have a rate limit of 30,000 purge API calls in every 24 hour period. source
• You may purge up to 30 tags in one API call, and make up to 30,000 purge API calls in every 24 hour period. source

I'm guessing that 30,000 is the new limit, and 2,000 was the limit they had in place while they were rolling this feature out, but it would be great to confirm that.

[vitaly-malashevsky]

We faced the same issue recently and when we've been reaching the limit of 2000 purges we still been able to purge more and more w/o any problems. Hence the actual limit is more than 2000.

[owenbush]

I have this patch successfully applied using our Drupal composer.json, it works nicely. Thanks.