Fix CI to explicitly activate prerelease profile for prerelease site

When CI set QUARTO_PROFILE=prerelease-docs, the profile group
[rc, prerelease] auto-added rc (the group default), giving the
prerelease site RC branding. Adding 'prerelease' explicitly
(prerelease,prerelease-docs) satisfies the group so the default
is not auto-added.

This also makes the prerelease site immune to "flip to RC" commits
that reorder the profile group, eliminating empty cherry-picks when
those commits are auto-backported to the prerelease branch.

Author: cderv

.github/workflows/preview.yml

@@ -103,7 +103,7 @@ jobs:
       - name: Render 
         uses: quarto-dev/quarto-actions/render@v2
         env:
-          QUARTO_PROFILE: ${{ steps.prerelease-docs-check.outputs.is_prerelease_docs == 'true' && 'prerelease-docs' || '' }}
+          QUARTO_PROFILE: ${{ steps.prerelease-docs-check.outputs.is_prerelease_docs == 'true' && 'prerelease,prerelease-docs' || '' }}
 
       - name: Deploy Preview to Netlify as preview
         id: netlify-deploy

.github/workflows/publish.yml

@@ -47,7 +47,7 @@ jobs:
       - name: Render 
         uses: quarto-dev/quarto-actions/render@v2
         env:
-          QUARTO_PROFILE: ${{ (inputs.prerelease || (contains(fromJSON('["push", "workflow_dispatch"]'), github.event_name) && github.ref == 'refs/heads/prerelease')) && 'prerelease-docs' || '' }}
+          QUARTO_PROFILE: ${{ (inputs.prerelease || (contains(fromJSON('["push", "workflow_dispatch"]'), github.event_name) && github.ref == 'refs/heads/prerelease')) && 'prerelease,prerelease-docs' || '' }}
 
       - name: Publish release website
         # Only do this step if