[ES|QL] indentation improvements (#217255)

## Summary

The formatter uses a tab size of 2 spaces. The editor should follow suit
so that it is easy to keep the formatting.

Also, the editor should keep the current indentation automatically.





https://github.com/user-attachments/assets/8c89b33a-2ba3-4332-a858-c5b8cb9c65dd

---------

Co-authored-by: Stratoula Kalafateli <efstratia.kalafateli@elastic.co>

src/platform/packages/private/kbn-esql-editor/src/esql_editor.tsx

@@ -681,7 +681,7 @@ export const ESQLEditor = memo(function ESQLEditor({
         above: false,
       },
       accessibilitySupport: 'off',
-      autoIndent: 'none',
+      autoIndent: 'keep',
       automaticLayout: true,
       fixedOverflowWidgets: true,
       folding: false,
@@ -713,6 +713,7 @@ export const ESQLEditor = memo(function ESQLEditor({
         verticalScrollbarSize: 6,
       },
       scrollBeyondLastLine: false,
+      tabSize: 2,
       theme: ESQL_LANG_ID,
       wordWrap: 'on',
       wrappingIndent: 'none',