enable 'quick' macro for databricks

[data-blade]

Describe the feature

quick_are_queries_identical is currently enable for BQ and Snowflake only. Enabling it for Databricks too only takes a minor change: using the Snowflake sql and replacing hash_agg with xxhash64.

Describe alternatives you've considered

none

Additional context

none

Who will this benefit?

users of dbt-databricks adapter

Are you interested in contributing this feature?

since this is a quick one, i already have a PR ready, but cannot push (probably need to be added as contributor?)