[ADAP-942] [Feature] Remove copy materialization

[dbeatty10]

Is this your first time submitting a feature request?

• I have read the expectations for open source contributors
• I have searched the existing issues, and I could not find an existing issue for this feature
• I am requesting a straightforward extension of existing dbt-bigquery functionality, rather than a Big Idea better suited to a discussion

Describe the feature

Per #820 (comment), add a deprecation warning for the copy materialization.

This is a follow-up to #964.

Optionally include upgrade instructions from here for those that rely upon this materialization.

Describe alternatives you've considered

No response

Who will this benefit?

No response

Are you interested in contributing this feature?

No response

Anything else?

No response

[dbeatty10]

In response to these options for replacement, @xemuliam raised the following:

Those two options will be working only if copy_table function won't be deleted from BigQuery adapter code

@xemuliam I see what you are saying about copy_table which in turn depends on copy_bq_table.

@dataders does this affect your thoughts on how best we can remove this materialization (or if we should)?

[github-actions]

This issue has been marked as Stale because it has been open for 180 days with no activity. If you would like the issue to remain open, please comment on the issue or else it will be closed in 7 days.

[github-actions]

Although we are closing this issue as stale, it's not gone forever. Issues can be reopened if there is renewed community interest. Just add a comment to notify the maintainers.