[Fix] Support for Spark versions with multiple Scala versions

[alexott]

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What changes are proposed in this pull request?

This is a fix for https://github.com/databricks/terraform-provider-databricks/issues/5218. The issue is cased by the fact that Scala selector had default value of 2.12 (for Terraform only), and as result was filtering out 17.x versions that are released only with Scala 2.13.

Fix is to relax the default value, but handle the case when there could be 2.12 and 2.13 versions for the same DBR version (16.x only).

Removed all Terraform customizations from the Go SDK struct, will be handled separately in Terraform itself

Also bumped staticcheck to 0.6.1 to support compilation with Go 1.25

How is this tested?

Added unit test, tested manually