Revert "Remove field preserveUnknownFields from CRDs"

This reverts commit cdaaf3d51c.

jsonnet/kube-prometheus/kube-prometheus.libsonnet

@@ -18,38 +18,7 @@ local configMapList = k3.core.v1.configMapList;
   kubePrometheus+:: {
     namespace: k.core.v1.namespace.new($._config.namespace),
   },
-  prometheusOperator+::
-  {
-    '0alertmanagerCustomResourceDefinition'+: {
-      spec: std.mergePatch(super.spec, {
-        preserveUnknownFields: null,
-      }),
-    },
-    '0prometheusCustomResourceDefinition'+: {
-      spec: std.mergePatch(super.spec, {
-        preserveUnknownFields: null,
-      }),
-    },
-    '0servicemonitorCustomResourceDefinition'+: {
-      spec: std.mergePatch(super.spec, {
-        preserveUnknownFields: null,
-      }),
-    },
-    '0podmonitorCustomResourceDefinition'+: {
-      spec: std.mergePatch(super.spec, {
-        preserveUnknownFields: null,
-      }),
-    },
-    '0prometheusruleCustomResourceDefinition'+: {
-      spec: std.mergePatch(super.spec, {
-        preserveUnknownFields: null,
-      }),
-    },
-    '0thanosrulerCustomResourceDefinition'+: {
-      spec: std.mergePatch(super.spec, {
-        preserveUnknownFields: null,
-      }),
-    },
+  prometheusOperator+:: {
     service+: {
       spec+: {
         ports: [