SpringBoot Build names don't match in release workflow

https://github.com/spring-projects/spring-boot/blob/a3c34b49362769c5ef65833e82a43f59c15e5dc6/.github/workflows/release.yml#L30

When the release, github.ref_name will be something like v3.2.11.

https://github.com/spring-projects/spring-boot/blob/a3c34b49362769c5ef65833e82a43f59c15e5dc6/.github/workflows/release.yml#L72

https://github.com/spring-projects/spring-boot/blob/a3c34b49362769c5ef65833e82a43f59c15e5dc6/.github/actions/sync-to-maven-central/action.yml#L28

https://github.com/spring-projects/spring-boot/blob/a3c34b49362769c5ef65833e82a43f59c15e5dc6/.github/workflows/release.yml#L86

When we release, needs.build-and-stage-release.outputs.version will be something like 3.2.11.

This mismatch means that both the artifact download and the build promotion will use the wrong build name and won't find anything to download/promote.

Instead of github.ref_name, we used to use steps.build-and-publish.outputs.version. We should probably go back to that unless there's good reason to use the ref_name instead.