Remove Arcus.Observability.Telemetry.Sql project

[stijnmoreels]

Is your feature request related to a problem? Please describe.
Once the SQL dependency logging extensions with the SQL connection string overloads are moved to the Arcus.Observability.Telemetry.Core, the remaining deprecated logging extensions in Arcus.Observability.Telemetry.Sql have no use anymore.

Describe the solution you'd like
Remove the entire Arcus.Observability.Telemetry.Sql project from the solution. Once v2.7 is released, we can mark that version of this package as deprecated and remove the project in the solution as no further versions will be released.