perf-tool: Force animations when running perf tests

This ensures we, unless there is a remote desktop connection explicitly
asking to disable animations, we'll run with animations despite e.g.
hardware acceleration is missing.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2560>

src/gnome-shell-perf-tool.in

@@ -45,6 +45,8 @@ def start_shell(wrap=None, perf_output=None):
         args += wrap.split(' ')
     args.append(os.path.join(self_dir, 'gnome-shell'))
 
+    args.append('--force-animations')
+
     if options.replace:
         args.append('--replace')