Revert "only dispose completion model when dispose suggest logic or when re-triggering, #75106"

This reverts commit 238a8521.

src/vs/editor/contrib/suggest/suggestModel.ts

@@ -226,6 +226,8 @@ export class SuggestModel implements IDisposable {
 				this._requestToken = undefined;
 			}
 			this._state = State.Idle;
+			dispose(this._completionModel);
+			this._completionModel = undefined;
 			this._context = undefined;
 			this._onDidCancel.fire({ retrigger });
 		}