Skip implementation plans in release notes

[sarayourfriend]

Problem

Implementation plans, if tagged with the stack(s) for the apps they are related to, will show in the release notes for the app.

However, this is inaccurate both from a changelog perspective and, once we implement #2264, will make it look like a release is needed without that being the case.

Description

Add the project: prefixed labels to list of skipped labels for the release drafter configs.

Additional context

Noticed with this changelog PR: 48f7d8d

Alternative

Be more mindful about explicitly adding skip changelog to PRs that make no releasable code changes.