[Data Streams] Unskip API integration tests (elastic#209102)

Closes elastic#209014

## Summary

This PR unskips and updates the Data streams API integration tests to
reflect the recent changes to Elasticsearch
(elastic/elasticsearch#121049). Previously, the
`cluster.logsdb.enabled` setting was always `false` by default in
stateful Kibana. With the new changes, it is `true` by default if the
`logsdb.prior_logs_usage` setting is `false` (which is the case for new
test clusters, hence the test failure), and `true` otherwise. Therefore,
we need to update the tests so that we test both cases.

Flaky test runner:
https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/7821

(cherry picked from commit 96e3d55)

x-pack/test/api_integration/apis/management/index_management/data_streams.ts

@@ -193,14 +193,22 @@ export default function ({ getService }: FtrProviderContext) {
             await deleteDataStream(logsdbDataStreamName);
           });
 
-          const logsdbSettings: Array<{ enabled: boolean | null; indexMode: string }> = [
-            { enabled: true, indexMode: 'logsdb' },
-            { enabled: false, indexMode: 'standard' },
-            { enabled: null, indexMode: 'standard' }, // In stateful Kibana, the cluster.logsdb.enabled setting is false by default, so standard index mode
+          const logsdbSettings: Array<{
+            enabled: boolean | null;
+            prior_logs_usage: boolean;
+            indexMode: string;
+          }> = [
+            { enabled: true, prior_logs_usage: true, indexMode: 'logsdb' },
+            { enabled: false, prior_logs_usage: true, indexMode: 'standard' },
+            // In stateful Kibana, if prior_logs_usage is set to true, the cluster.logsdb.enabled setting is false by default, so standard index mode
+            { enabled: null, prior_logs_usage: true, indexMode: 'standard' },
+            // In stateful Kibana, if prior_logs_usage is set to false, the cluster.logsdb.enabled setting is true by default, so logsdb index mode
+            { enabled: null, prior_logs_usage: false, indexMode: 'logsdb' },
           ];
 
-          logsdbSettings.forEach(({ enabled, indexMode }) => {
-            it(`returns ${indexMode} index mode if logsdb.enabled setting is ${enabled}`, async () => {
+          // eslint-disable-next-line @typescript-eslint/naming-convention
+          logsdbSettings.forEach(({ enabled, prior_logs_usage, indexMode }) => {
+            it(`returns ${indexMode} index mode if logsdb.enabled setting is ${enabled} and logs.prior_logs_usage is ${prior_logs_usage}`, async () => {
               await es.cluster.putSettings({
                 body: {
                   persistent: {
@@ -209,6 +217,9 @@ export default function ({ getService }: FtrProviderContext) {
                         enabled,
                       },
                     },
+                    logsdb: {
+                      prior_logs_usage,
+                    },
                   },
                 },
               });