Warn about removal of deprecated format strings (#33829)

Co-authored-by: becker33 <becker33@users.noreply.github.com>

etc/spack/defaults/config.yaml

@@ -19,7 +19,7 @@ config:
   install_tree:
     root: $spack/opt/spack
     projections:
-      all: "${ARCHITECTURE}/${COMPILERNAME}-${COMPILERVER}/${PACKAGE}-${VERSION}-${HASH}"
+      all: "${architecture}/${compiler.name}-${compiler.version}/${name}-${version}-${hash}"
     # install_tree can include an optional padded length (int or boolean)
     # default is False (do not pad)
     # if padded_length is True, Spack will pad as close to the system max path
@@ -214,4 +214,4 @@ config:
 
   # Number of seconds a buildcache's index.json is cached locally before probing
   # for updates, within a single Spack invocation. Defaults to 10 minutes.
-  binary_index_ttl: 600
+  binary_index_ttl: 600