STRING_AGG not recognized after updating from EFCore 6 to EFCore 7

Hello, I have run into an issue after upgrading from EFCore 6 to EFCore 7. Previously, the below query was working though the select portion was running client-side, as the string,Join method was unable to be translated.

After upgrading to EFCore 7, it seems that it has been implemented using STRING_AGG. However, we are still using SQL Server 2016 which does not support it (Trying to get us to upgrade but I don't know how soon that may happen).

I'm wondering if there is some way to target EFCore 7 for a specific version of SQL Server (i.e. 2016) and have it fall back to client-side evaluation? I have not seen any method of doing this though so I wanted to see if there are any suggestions or fixes.

I'm hoping to avoid having to modify all of the code where we may be doing this to force client-side evaluation.

This also was not part of the breaking changes when upgrading to EFCore7, so it isn't obvious until runtime as well.

Thank you for any help!

```C#
from appraisals in _assessorContext.LienDateAppraisal
join status in _assessorContext.LienDateAppraisalStatus.Where(x => x.Name == StatusSubmitted) on
appraisals.Status equals status.Id
join locks in _assessorContext.LienDateAppraisalLocks on appraisals.Assessment equals locks.Assessment
into appraisalLocks
from locks in appraisalLocks.DefaultIfEmpty()
select new { appraisals, locks } into appraisalLocks
group appraisalLocks by new { appraisalLocks.appraisals.Assessment } into appraisalLocks
select new
{
appraisalLocks.Key.Assessment,
Triggers = string.Join(", ", appraisalLocks.Select(x => x.appraisals.Trigger)),
Locks = appraisalLocks.Select(x => x.locks).First() ?? new LienDateAppraisalLocks(),
Count = appraisalLocks.Count(),
Date = appraisalLocks.Min(x => x.appraisals.StatusChangeTDS)
}
```

```
STRING_AGG' is not a recognized built-in function name.\r\nIncorrect syntax near the keyword 'AS'.\r\nIncorrect syntax near the keyword 'AS'.
```

EF Core version: 7.0.1
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: .NET 7.0
Operating system: Windows Server 2016
IDE: Visual Studio 2022 17.4.326.54890