SearchKit - Fix aggregated joins

[colemanw]

Overview

Fixes a bug where adding an aggregated join will cause invalid SQL.

Before

The following search will crash:
SEARCH FOR: Activities
WITH (optional): Activity Contacts
GROUP BY: Activity ID

After

Search runs without error.

Comments

When merging this forward, the first commit is already in master and can be skipped over if git complains.

[civibot]

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[eileenmcnaughton]

@colemanw I'm not managing to replicate this - but @kurund if this fixes for you please merge

[kurund]

@colemanw @eileenmcnaughton

Thank you. Tested above on master and it working as expected. Did few more random tests and all good.

IMO good to merge.

[kurund]

Also tested on 5.42 branch and also working fine.

[colemanw]

Thanks @kurund - can you also check this further improvement I did in master: #21420