test: Fix legacy upgrade tests catalog impl (#25324)

This legacy upgrade test will skip versions when testing certain upgrade
paths. The persist catalog will panic if a version is skipped when
upgrading. Even when using the stash catalog implementation we open the
persist catalog during boot, which will cause the panic. To avoid this,
this commit uses the emergency-stash catalog implementation, which
doesn't even attempt to open the persist catalog.

Fixes #25321

ci/test/pipeline.template.yml

@@ -282,7 +282,6 @@ steps:
 
   - id: legacy-upgrade
     label: Legacy upgrade tests (last version from docs)
-    skip: "failing, to be addressed with #25321"
     depends_on: build-aarch64
     timeout_in_minutes: 60
     artifact_paths: junit_*.xml

test/legacy-upgrade/mzcompose.py

@@ -42,7 +42,11 @@
         options=list(mz_options.values()),
         volumes_extra=["secrets:/share/secrets"],
         external_cockroach=True,
-        catalog_store="stash",
+        # This test will skip versions when testing certain upgrade paths. The persist catalog
+        # will panic if a version is skipped when upgrading. Even when using the stash
+        # implementation we open the persist catalog, which will cause the panic. To avoid this, we
+        # use the emergency-stash, which doesn't even attempt to open the persist catalog.
+        catalog_store="emergency-stash",
     ),
     # N.B.: we need to use `validate_catalog_store=None` because testdrive uses
     # HEAD to load the catalog from disk but does *not* run migrations. There
@@ -141,7 +145,7 @@ def test_upgrade_from_version(
             ],
             volumes_extra=["secrets:/share/secrets"],
             external_cockroach=True,
-            catalog_store="stash",
+            catalog_store="emergency-stash",
         )
         with c.override(mz_from):
             c.up("materialized")