build: Rename centos-bootc.yaml to centos-stream-9-tier-1.yaml

When we went back to the "one big image" model we simplified
things to just `centos-bootc.yaml`.  But since stream10 is
here, and I think we do want to revisit having smaller images,
let's rename it back.

Signed-off-by: Colin Walters <walters@verbum.org>

Containerfile.centos-stream9

@@ -26,7 +26,7 @@
 FROM quay.io/centos/centos:stream9 as repos
 
 FROM quay.io/centos-bootc/bootc-image-builder:latest as builder
-ARG MANIFEST=centos-bootc.yaml
+ARG MANIFEST=centos-stream-9-tier1.yaml
 # XXX: we should just make sure our in-tree c9s repo points to the c9s paths and doesn't require vars to avoid these steps entirely
 COPY --from=repos /etc/dnf/vars /etc/dnf/vars
 COPY --from=repos /etc/yum.repos.d/centos.repo c9s.repo