Source Intercom: Support high volume syncs

## Tell us about the problem you're trying to solve
A user was trying to sync a high volume instance of Intercom (logs below). The connector spent many hours (50+ hours) syncing data from the contacts stream. This is a bad user experience as it does not allow them to make use of the product and data quickly.
[logs-97415.txt](https://github.com/airbytehq/airbyte/files/8383210/logs-97415.txt)

Note that this issue is not just trying to do this for intercom, but should be used as a learning opportunity for how this can be done at the CDK level as described in airbytehq/airbyte-internal-issues#504

## Describe the solution you’d like
I would like us to find a way to speed up intercom syncs coming from high volume instances such as this one. Ideally a sync takes no longer than a couple of hours in 99% of cases.