Browser plugin doesn't use the configured SourceGraph URL

Created by: Al3xCalibur

• Sourcegraph plugin version: 21.10.15.1603
• Platform information: Browser extension - Firefox

Steps to reproduce:

1. Add a SourceGraph self-hosted in the plugin options
2. Use src SomethingToSearch

Expected behavior:

The plugin opens a new tab with the self-hosted URL

Actual behavior:

The plugin opens a new tab with the default SourceGraph URL