[Observability] [Alert details page] Follow up to fix view in discover link is partial broken (elastic#226847)

## Summary

This is a follow-up on #elastic#217993
and that fixes elastic#212133 by adding a missing check/case

Author: fkanout

x-pack/solutions/observability/plugins/observability/common/custom_threshold_rule/get_view_in_app_url.test.ts

@@ -302,7 +302,7 @@ describe('getViewInAppUrl', () => {
       { spaceId }
     );
   });
-  it('should call getRedirectUrl with dataViewSpec', () => {
+  it('should call getRedirectUrl with dataViewSpec of the AD-HOC data view', () => {
     const spaceId = 'mockedSpaceId';
     const dataViewSpec = {
       id: 'mockedDataViewId',
@@ -345,4 +345,39 @@ describe('getViewInAppUrl', () => {
       { spaceId }
     );
   });
+  it('should call getRedirectUrl with the id of the SAVED data view ', () => {
+    const spaceId = 'mockedSpaceId';
+    const mockedDataViewId = 'uuid-mocked-dataView-id';
+    const args: GetViewInAppUrlArgs = {
+      dataViewId: mockedDataViewId,
+      searchConfiguration: {
+        index: 'uuid-mockedDataViewId',
+        query: {
+          language: '',
+          query: 'mockedFilter',
+        },
+        filter: [],
+      },
+      logsLocator,
+      startedAt,
+      endedAt,
+      spaceId,
+    };
+
+    expect(getViewInAppUrl(args)).toBe('mockedGetRedirectUrl');
+    expect(logsLocator.getRedirectUrl).toHaveBeenCalledWith(
+      {
+        dataset: undefined,
+        dataViewSpec: undefined,
+        dataViewId: mockedDataViewId,
+        timeRange: returnedTimeRange,
+        filters: [],
+        query: {
+          query: 'mockedFilter',
+          language: 'kuery',
+        },
+      },
+      { spaceId }
+    );
+  });
 });

x-pack/solutions/observability/plugins/observability/common/custom_threshold_rule/get_view_in_app_url.ts

@@ -58,9 +58,15 @@ export const getViewInAppUrl = ({
     query.query = searchConfigurationQuery;
   }
   let dataViewSpec;
-  if (searchConfiguration?.index && !isEmpty(searchConfiguration?.index)) {
+
+  if (
+    typeof searchConfiguration?.index === 'object' &&
+    searchConfiguration.index !== null &&
+    !isEmpty(searchConfiguration.index)
+  ) {
     dataViewSpec = searchConfiguration.index as DataViewSpec;
   }
+
   return logsLocator.getRedirectUrl(
     {
       dataViewId,

x-pack/test/api_integration/deployment_agnostic/apis/observability/alerting/custom_threshold/avg_pct_fired.ts

@@ -279,7 +279,6 @@ export default function ({ getService }: DeploymentAgnosticFtrProviderContext) {
         expect(resp.hits.hits[0]._source?.viewInAppUrl).contain('DISCOVER_APP_LOCATOR');
         expect(omit(parsedViewInAppUrl.params, 'timeRange.from')).eql({
           dataViewId: DATA_VIEW_ID,
-          dataViewSpec: DATA_VIEW_ID,
           timeRange: { to: 'now' },
           query: { query: '', language: 'kuery' },
           filters: [],

x-pack/test/api_integration/deployment_agnostic/apis/observability/alerting/custom_threshold/avg_pct_no_data.ts

@@ -235,7 +235,6 @@ export default function ({ getService }: DeploymentAgnosticFtrProviderContext) {
         expect(resp.hits.hits[0]._source?.viewInAppUrl).contain('DISCOVER_APP_LOCATOR');
         expect(omit(parsedViewInAppUrl.params, 'timeRange.from')).eql({
           dataViewId: DATA_VIEW_ID,
-          dataViewSpec: DATA_VIEW_ID,
           timeRange: { to: 'now' },
           query: { query: '', language: 'kuery' },
           filters: [],

x-pack/test/api_integration/deployment_agnostic/apis/observability/alerting/custom_threshold/avg_ticks_fired.ts

@@ -277,7 +277,6 @@ export default function ({ getService }: DeploymentAgnosticFtrProviderContext) {
         expect(resp.hits.hits[0]._source?.viewInAppUrl).contain('DISCOVER_APP_LOCATOR');
         expect(omit(parsedViewInAppUrl.params, 'timeRange.from')).eql({
           dataViewId: DATA_VIEW_ID,
-          dataViewSpec: DATA_VIEW_ID,
           timeRange: { to: 'now' },
           query: { query: '', language: 'kuery' },
           filters: [],

x-pack/test/api_integration/deployment_agnostic/apis/observability/alerting/custom_threshold/cardinality_runtime_field_fired.ts

@@ -280,7 +280,6 @@ export default function ({ getService }: DeploymentAgnosticFtrProviderContext) {
         expect(resp.hits.hits[0]._source?.viewInAppUrl).contain('DISCOVER_APP_LOCATOR');
         expect(omit(parsedViewInAppUrl.params, 'timeRange.from')).eql({
           dataViewId: DATA_VIEW_ID,
-          dataViewSpec: DATA_VIEW_ID,
           timeRange: { to: 'now' },
           query: { query: '', language: 'kuery' },
           filters: [],

x-pack/test/api_integration/deployment_agnostic/apis/observability/alerting/custom_threshold/documents_count_fired.ts

@@ -266,7 +266,6 @@ export default function ({ getService }: DeploymentAgnosticFtrProviderContext) {
         expect(resp.hits.hits[0]._source?.viewInAppUrl).contain('DISCOVER_APP_LOCATOR');
         expect(omit(parsedViewInAppUrl.params, 'timeRange.from')).eql({
           dataViewId: DATA_VIEW_ID,
-          dataViewSpec: DATA_VIEW_ID,
           timeRange: { to: 'now' },
           query: { query: 'host.name:* and container.id:*', language: 'kuery' },
           filters: [],