Fix ace editor warnings (#18893)

* Fix ace editor warnings

x-pack/plugins/index_management/__jest__/components/index_table.test.js

@@ -32,6 +32,7 @@ jest.mock('react-ace', () => {
     }
   };
 });
+jest.mock('brace/theme/textmate', () => 'brace/theme/textmate');
 
 setHttpClient(axios.create());
 let server = null;

x-pack/plugins/index_management/public/sections/index_list/components/detail_panel/show_json/show_json.js

@@ -7,6 +7,8 @@
 import React from "react";
 import { EuiCodeEditor } from "@elastic/eui";
 
+import 'brace/theme/textmate';
+
 export class ShowJson extends React.PureComponent {
   componentWillMount() {
     this.props.loadIndexData(this.props);
@@ -26,10 +28,13 @@ export class ShowJson extends React.PureComponent {
     return (
       <EuiCodeEditor
         mode="json"
-        theme="github"
+        theme="textmate"
         isReadOnly
         setOptions={{ maxLines: Infinity }}
         value={json}
+        editorProps={{
+          $blockScrolling: Infinity
+        }}
       />
     );
   }