Exclude repo filter doesn't exclude private repos

Created by: gabtorre

• Sourcegraph version: 3.33.0
• Platform information: Kubernetes, Docker Compose

Steps to reproduce:

1. Run a query with the -repo: filter to exclude a private repo

Expected behavior:

The private repo is excluded from the results.

Actual behavior:

The private repo is included in the results. __

The -repo: filter seems to exclude public repos as intended on 3.33.0.