ci: upsert license key for backend integration tests
Created by: unknwon
Blocked by https://github.com/sourcegraph/infrastructure/pull/3862
We are going to require a valid license key for repository permissions in https://github.com/sourcegraph/sourcegraph/pull/40826, thus we also need one for backend integration tests as a prerequisite.
Test plan
CI and manually tested
cc @miveronese