Bogus "The target principal name is incorrect" on connecting to "."

### Describe the bug

With a connection string that reads "Server=.;Database=...", trying to connect to SQL Server with a fully valid certificate does not work.

If you are seeing an exception, include the full exceptions details (message and stack trace).

```
Microsoft.Data.SqlClient.SqlException
HResult=0x80131904
Message=A connection was successfully established with the server, but then an error occurred during the login process. (provider: SSL Provider, error: 0 - The target principal name is incorrect.)
Source=Core Microsoft SqlClient Data Provider
StackTrace:
at Microsoft.Data.SqlClient.Connection.SqlConnectionInternal.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)

Inner Exception 1:
Win32Exception: The target principal name is incorrect.
```

### To Reproduce

1) Have SQL Server
2) Have loaded SQL Certificate

### Expected behavior

Any certificate that is valid for the current hostname is valid for .

My certificate is issued for hostname.domain.name , hostname, and localhost. The certificate should pass.

### Further technical details
Microsoft.Data.SqlClient version: 7.0.0
.NET target: .NET 10
SQL Server version: SQL 16 (why? to load backup files from SQL 16 of course)
Operating system: Windows 11

**Additional context**

Changing . to localhost does work; assuming nobody tampered with DNS lookup for localhost. But I shouldn't have to depend on that. . exists as an alias for a reason.

It is not possible to issue a certificate for . as that will be interpreted as a certificate that's valid _for the root domain_.