Add a template to the restore E2E test

This helped me reproduce a race in "pg_ctl start" during Postgres recovery.

Issue: PGO-1945

Author: cbandy

testing/chainsaw/e2e/pgbackrest-restore/change-parameters.yaml

@@ -0,0 +1,62 @@
+apiVersion: chainsaw.kyverno.io/v1alpha1
+kind: StepTemplate
+metadata:
+  name: change-parameters
+spec:
+  try:
+    -
+      description: >
+        Read the timestamp at which PostgreSQL last started
+      script:
+        outputs: [{ name: before, value: (trim_space($stdout)) }]
+        content: |
+          PRIMARY=$(
+            kubectl get pod --namespace "${NAMESPACE}" \
+              --output name --selector '
+                postgres-operator.crunchydata.com/cluster=original,
+                postgres-operator.crunchydata.com/role=master'
+          )
+
+          kubectl exec --namespace "${NAMESPACE}" "${PRIMARY}" \
+            -- psql -qAt --command 'SELECT pg_postmaster_start_time()'
+
+    - patch:
+        resource:
+          apiVersion: postgres-operator.crunchydata.com/v1beta1
+          kind: PostgresCluster
+          metadata:
+            name: original
+          spec:
+            config:
+              parameters: ($parameters)
+
+    -
+      description: >
+        Wait for Postgres to restart, signal the WAL archiver, then wait for WAL to archive
+      script:
+        timeout: 30s
+        env: [{ name: BEFORE, value: ($before) }]
+        content: |
+          PRIMARY=$(
+            kubectl get pod --namespace "${NAMESPACE}" \
+              --output name --selector '
+                postgres-operator.crunchydata.com/cluster=original,
+                postgres-operator.crunchydata.com/role=master'
+          )
+
+          while true; do
+            START=$(
+              kubectl exec --namespace "${NAMESPACE}" "${PRIMARY}" \
+                -- psql -qAt --command 'SELECT pg_postmaster_start_time()'
+            )
+            if [ "${START}" ] && [ "${START}" != "${BEFORE}" ]; then break; else sleep 1; fi
+          done
+          echo "${START} != ${BEFORE}"
+
+          kubectl exec --namespace "${NAMESPACE}" "${PRIMARY}" \
+            -- psql -qb --command "SELECT pg_stat_reset_shared('archiver')" --command 'SELECT pg_switch_wal()'
+
+          while [ 0 = "$(
+            kubectl exec --namespace "${NAMESPACE}" "${PRIMARY}" \
+              -- psql -qAt --command 'SELECT archived_count FROM pg_stat_archiver'
+          )" ]; do sleep 1; done