[REF] web: sample server: _mockReadGroup

The function used to group fake records in _mockReadGroup was
overcomplicated. We simplify it.

closes odoo/odoo#108921

Signed-off-by: Aaron Bohy (aab) <aab@odoo.com>

addons/web/static/src/views/sample_server.js

@@ -436,14 +436,7 @@ export class SampleServer {
         const groups = arrayGroupBy(records, (record) => {
             const vals = {};
             for (const gb of normalizedGroupBys) {
-                const { fieldName, type } = gb;
+                vals[gb.fieldName] = record[gb.fieldName];
-                let value;
-                if (["date", "datetime"].includes(type)) {
-                    value = this._formatValue(record[fieldName], gb);
-                } else {
-                    value = record[fieldName];
-                }
-                vals[fieldName] = value;
             }
             return JSON.stringify(vals);
         });