ref(routes): Avoid usage of optional route params

The syntax has changed in react-router 6. Instead of trying to build
compatability we can just remove the one optional route we have.

static/app/routes.tsx

@@ -1705,12 +1705,9 @@ function buildRoutes() {
  );
 
  const issueListRoutes = (
- <Route
- path="/issues/(searches/:searchId/)"
- component={errorHandler(IssueListContainer)}
- withOrgPath
- >
+ <Route path="/issues" component={errorHandler(IssueListContainer)} withOrgPath>
  <IndexRoute component={errorHandler(IssueListOverview)} />
+ <Route path="searches/:searchId/" component={errorHandler(IssueListOverview)} />
  </Route>
  );