qa: extensions test fails in CI

Created by: davejrt

When running yarn test:regression:extensions in CI, the test fails with the following error:

    sourcegraph-qa-test:   2 passing (30s)
    sourcegraph-qa-test:   1 failing
    sourcegraph-qa-test:   1) Sourcegraph extensions regression test suite
    sourcegraph-qa-test:        Codecov extension:
    sourcegraph-qa-test:      Error: expect(received).toHaveLength(expected)
    sourcegraph-qa-test:
    sourcegraph-qa-test: Expected length: 264
    sourcegraph-qa-test: Received length: 0
    sourcegraph-qa-test: Received array:  []
    sourcegraph-qa-test:       at /sourcegraph/client/web/src/regression/extensions.test.ts:77:93
    sourcegraph-qa-test:       at processTicksAndRejections (internal/process/task_queues.js:93:5)
    sourcegraph-qa-test:       at RetryOperation._fn (/sourcegraph/node_modules/p-retry/index.js:41:12)
    sourcegraph-qa-test:

Full run with artifacts here: https://buildkite.com/sourcegraph/qa/builds/92#4e123c29-eb1e-4626-a210-b56e028d2545