feat(ingest/databricks): ingest hive metastore by default, more docs

[mayurinehate]

Checklist

• The PR conforms to DataHub's Contributing Guideline (particularly Commit Message Format)
• Links to related issues (if applicable)
• Tests for the changes have been added/updated (if applicable)
• Docs related to the changes have been added/updated (if applicable). If a new feature has been added a Usage Guide has been added for the same.
• For any breaking change/potential downtime/deprecation/big changes an entry has been made in Updating DataHub

[hsheth2]

let's call out that this is a breaking change?

It might also be good to show examples of what the hierarchy would look like when this is true/false

[hsheth2]

also we should say we recommend keeping this set to false, and that folks should use platform_instance instead

[mayurinehate]

I'll add the section in doc about hierarchy + update description of include_metastore config field.

As far as I understand, we'll get rid of this config, eventually. So the section would not be relevant - post that.

[mayurinehate]

1. added in updating-datahub.md as a breaking change
2. added the examples in updating-datahub doc, I believe, you meant this only and not to add this in source docs ?
3. we already have pydantic validator for warning if this is not set to false, so we are covered there. changed the error message to represent current state.