Revert prsTreeModel.ts cache invalidation approach

Agent-Logs-Url: https://github.com/microsoft/vscode-pull-request-github/sessions/001ddef0-6d36-4dcc-96f7-ed3f3d2901e5

Co-authored-by: alexr00 <38270282+alexr00@users.noreply.github.com>

Author: Copilot

src/view/prsTreeModel.ts

@@ -87,18 +87,7 @@ export class PrsTreeModel extends Disposable {
 				if (e.new) {
 					prs.push({ model: e.new, event: {} });
 				}
-
-				// When a new active PR is discovered (e.g. PR created on GitHub website),
-				// check if it's already in the local PR cache. If not, clear the local cache
-				// and fire a full folder refresh so the "Local Pull Request Branches" category
-				// picks up the newly-associated branch.
-				if (e.new && !this._allCachedPRs.has(e.new)) {
-					const cache = this.getFolderCache(manager);
-					cache.delete(PRType.LocalPullRequest);
-					this._onDidChangeData.fire(manager);
-				} else {
-					this._onDidChangeData.fire(prs);
-				}
+				this._onDidChangeData.fire(prs);
 
 				if (this._activePRDisposables.has(manager)) {
 					disposeAll(this._activePRDisposables.get(manager)!);