feat: expose update strategy for workloads

This commit introduces a new `updateStrategy` field for
statefulset-based workloads (Prometheus, PrometheusAgent, Alertmanager
and ThanosRuler). While for now, there's a 1:1 mapping with StatefulSet
strategies, it paves the way to the introduction of custom strategies
which may be required to streamline operations in case of broken updates
(similar to the scenario explained in
https://kubernetes.io/docs/concepts/workloads/controllers/statefulset/#forced-rollback).

Closes #5435

Signed-off-by: Simon Pasquier <spasquie@redhat.com>

test/e2e/prometheus_test.go

@@ -4877,6 +4877,31 @@ func testPrometheusCRDValidation(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "invalid-updateStrategy",
+			prometheusSpec: monitoringv1.PrometheusSpec{
+				CommonPrometheusFields: monitoringv1.CommonPrometheusFields{
+					Replicas: &replicas,
+					UpdateStrategy: &monitoringv1.StatefulSetUpdateStrategy{
+						Type: monitoringv1.StatefulSetUpdateStrategyType(""),
+					},
+				},
+			},
+			expectedError: true,
+		},
+		{
+			name: "invalid-ondelete-with-rollingupdate",
+			prometheusSpec: monitoringv1.PrometheusSpec{
+				CommonPrometheusFields: monitoringv1.CommonPrometheusFields{
+					Replicas: &replicas,
+					UpdateStrategy: &monitoringv1.StatefulSetUpdateStrategy{
+						Type:          monitoringv1.OnDeleteStatefulSetStrategyType,
+						RollingUpdate: &monitoringv1.RollingUpdateStatefulSetStrategy{},
+					},
+				},
+			},
+			expectedError: true,
+		},
 	}
 
 	for _, test := range tests {