Plugin deploy workflow does not work for initial plugin deployment

Bug Description

I just did a dry run test of deploying the view-transitions plugin in a first version (see #1997).

The workflow failed because in the "Check if deployment is needed" step the workflow makes an API request to WordPress.org, which leads to a 404 because the plugin isn't launched yet. So it's not the right conclusion to not deploy because of that.

We should probably change it so that:

• either a 404 error just leads to deploy=true being set, because there is no version deployed yet
• or (maybe safer) for new plugins we require an extra flag to still proceed in this case (or bypass the whole check entirely)

Here's the failing workflow: https://github.com/WordPress/performance/actions/runs/15401715502/job/43335668619

Start with the failing workflow run and inspect the "Check if deployment is needed" step, especially its WordPress.org API request and handling of a 404 response. Confirm the intended behavior for an initial plugin deployment with a maintainer, then verify that the workflow no longer skips a valid first deployment and still handles existing plugins correctly.