Use pg 15 in github kuttl tests

Author: dsessler7

.github/workflows/test.yaml

@@ -102,7 +102,7 @@ jobs:
           prefetch-timeout: 5m
           prefetch-images: |
             registry.developers.crunchydata.com/crunchydata/crunchy-pgbackrest:ubi9-2.56.0-2547
-            registry.developers.crunchydata.com/crunchydata/crunchy-postgres:ubi9-17.7-2547
+            registry.developers.crunchydata.com/crunchydata/crunchy-postgres:ubi8-15.15-2547
             registry.developers.crunchydata.com/crunchydata/crunchy-postgres:ubi9-16.11-2547
             registry.developers.crunchydata.com/crunchydata/crunchy-pgbouncer:ubi9-1.24-2547
             registry.developers.crunchydata.com/crunchydata/crunchy-postgres-exporter:ubi9-0.18.1-2547
@@ -134,20 +134,14 @@ jobs:
             --env 'RELATED_IMAGE_PGEXPORTER=registry.developers.crunchydata.com/crunchydata/crunchy-postgres-exporter:ubi9-0.18.1-2547' \
             --env 'RELATED_IMAGE_PGUPGRADE=registry.developers.crunchydata.com/crunchydata/crunchy-upgrade:ubi9-18.1-2547' \
             --env 'RELATED_IMAGE_POSTGRES_16=registry.developers.crunchydata.com/crunchydata/crunchy-postgres:ubi9-16.11-2547' \
-            --env 'RELATED_IMAGE_POSTGRES_17=registry.developers.crunchydata.com/crunchydata/crunchy-postgres:ubi9-17.7-2547' \
+            --env 'RELATED_IMAGE_POSTGRES_15=registry.developers.crunchydata.com/crunchydata/crunchy-postgres:ubi8-15.15-2547' \
             --env 'RELATED_IMAGE_STANDALONE_PGADMIN=registry.developers.crunchydata.com/crunchydata/crunchy-pgadmin4:ubi9-9.8-2547' \
             --env 'RELATED_IMAGE_COLLECTOR=registry.developers.crunchydata.com/crunchydata/postgres-operator:ubi9-5.8.5-0' \
             --env 'PGO_FEATURE_GATES=TablespaceVolumes=true,OpenTelemetryLogs=true,OpenTelemetryMetrics=true' \
             --name 'postgres-operator' ubuntu \
             postgres-operator
 
       - run: make generate-kuttl
-        env:
-          KUTTL_PG_UPGRADE_FROM_VERSION: '16'
-          KUTTL_PG_UPGRADE_TO_VERSION: '17'
-          KUTTL_PG_VERSION: '16'
-          KUTTL_POSTGIS_VERSION: '3.4'
-          KUTTL_PSQL_IMAGE: 'registry.developers.crunchydata.com/crunchydata/crunchy-postgres:ubi9-16.11-2547'
       - run: |
           make check-kuttl && exit
           failed=$?