[4.0] Improve contact list performance on multilingual sites

[SharkyKZ]

Pull Request for Issue # .

Summary of Changes

Replaces JOIN and GROUP clauses in query with a subquery for improved performance.

Testing Instructions

Set up a multilingual site.
Enable language associations.
Create some contacts with and without associations
View contact list in backend.

Expected result

Works like before.

Documentation Changes Required

No.

[richard67]

I have tested this item ✅ successfully on 399b681

Tested with MySQL 5.7 and PostgreSQL 10.10.

About performance I can't say anything because my test data set is too small.

But I can confirm everything works as well as before, carefully watching PHP error log with PHP error reporting set to maximum and watching database log.

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[alikon]

I have tested this item ✅ successfully on 399b681

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[alikon]

RTC

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[wilsonge]

Thanks!