Simplify groupContactCache - remove redundant query

[colemanw]

Overview

Removes an unnecessary query when filling the smart group cache.

Before

This was essentially running the same query twice, once with COUNT and then again with INSERT.

After

Skip the count as the INSERT will do nothing if there are no results.

Comments

This refactoring is toward supporting API-based smart groups. See #17003

[civibot]

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[colemanw]

retest this please

[mattwire]

@seamuslee001 I'm trying to work out why we put this check in in the first place? Do you see any reason?

@colemanw I want to test this on one of the original sites that we did the cache work on. But I need to upgrade them to 5.24 (this weekend) - so will get back to you on a review asap!

[mattwire]

I've tested this and it seems to be working fine.

[colemanw]

Thanks @mattwire! Now we can turn our attention to testing out #17003 - it's mostly a new feature although it does involve some cleanup of old code, so we just need to ensure it doesn't cause regressions. If you have a site with smart groups you can test it on, that'd be great!