(core) Fix mislabeled telemetry metadata

Summary:
The oldFormula and newFormula metadata fields had their names switched by
mistake.

Test Plan: N/A

Reviewers: JakubSerafin

Reviewed By: JakubSerafin

Differential Revision: https://phab.getgrist.com/D3976

app/client/widgets/FormulaAssistant.ts

@@ -311,8 +311,8 @@ export class FormulaAssistant extends Disposable {
   private _saveOrClose() {
     if (this._hasExpanded) {
       this._logTelemetryEvent('assistantSave', true, {
-        newFormula: this._options.column.formula.peek(),
+        oldFormula: this._options.column.formula.peek(),
-        oldFormula: this._options.editor.getTextValue(),
+        newFormula: this._options.editor.getTextValue(),
       });
     }
     this._action = 'save';