Update behavior change format on upgrade guides

[mirnawong1]

Contributions

• I have read the contribution docs, and understand what's expected of me.

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

Per @matthewshaver 's comment in this PR review, he suggests that we either link to the section that explains what Introduced means or remove it when writing about behavior flags/changes? He mentions that using those words stands out and raises questions. Maybe these could say Disabled by default after the feature name rather than before.

It looks like a previous upgrade guide uses the same format: https://docs.getdbt.com/docs/dbt-versions/core-upgrade/upgrading-to-v1.8#managing-changes-to-legacy-behaviors so raising an issue to address this overall.

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

https://docs.getdbt.com/docs/dbt-versions/core-upgrade/upgrading-to-v1.8#managing-changes-to-legacy-behaviors
https://docs.getdbt.com/docs/dbt-versions/core-upgrade/upgrading-to-v1.9#new-and-changed-features-and-functionality

Additional information

No response