advise users to minimize objects & schemas for better performance

### Contributions

- [X] I have read the contribution docs, and understand what's expected of me.

### Link to the page on docs.getdbt.com requiring updates

I'm really not sure where this should go, because it applies to virtually any data platform

### What part(s) of the page would you like to see updated?

via @extrospective's https://github.com/dbt-labs/dbt-snowflake/issues/1034

we should tell folks that wherever possible, to limit the number of schemas and objects within those schemas that exist. This doesn't just refer to the number of models but rather the pre-existing schemas tables and views

### Additional information

_No response_