[FEATURE] - Deprecate collect_freshness macro in v0.5.0 release

The [collect_freshness](https://github.com/fivetran/dbt_fivetran_utils/blob/v0.4.10/macros/collect_freshness.sql) is a macro used to ensure that the source freshness test doesn't fail for cases when a Fivetran dbt package has disabled a source. Previously, if a source was disabled in a package, the freshness test would still fail. This macro ensured that it would not fail.

However, in the recent versions of dbt-core there is now a native feature (see example [here](https://github.com/fivetran/dbt_zendesk_source/blob/92b09230c5b4528c3d2d1b36bb24d653f57b6670/models/src_zendesk.yml#L91-L95)) which allows sources to be enabled/disabled based on a tag. Therefore, this macro will no longer be necessary once we move to the v0.5.0 release of fivetran_utils and only support dbt-core versions of v1.8.0 or greater.

Once we move to v0.5.0 of Fivetran Utils and update all Fivetran dbt packages to support this version, we will fully remove the collect_freshness macro from the fivetran_utils dbt package.