Increase MAX_FORM_MEMORY_SIZE after Flask upgrade

After 150dae4 we bumped Flask to 3.1
which started adding a limit to the maximum size a form field can be to
500KB by default. On cc-perf.igalia.com the runs that are submitted are
around 5MB, so submissions started failing with a 413
RequestEntityTooLarge error.

This increases it to 10MB to fix the error.

Author: lukel97

lnt/server/ui/app.py

@@ -224,6 +224,10 @@ def __init__(self, name):
         self.wsgi_app = RootSlashPatchMiddleware(self.wsgi_app)
         self.logger.setLevel(logging.DEBUG)
 
+        # Submitted runs can be pretty large so increase the maximum allowed
+        # form field size to 10MB to prevent 413 errors.
+        self.config['MAX_FORM_MEMORY_SIZE'] = 10_000_000
+
     def load_config(self, instance):
         self.instance = instance
         self.old_config = self.instance.config