Fix e2e create room tests
Fix e2e create room tests
The left-menu create menu bar button class we were targeting was removed in https://gitlab.com/gitlab-org/gitter/webapp/-/merge_requests/1853/diffs#note_336311496 but we didn't know because the e2e tests weren't able to run in CI, https://gitlab.com/gitlab-org/gitter/webapp/-/issues/2495
Testing strategy
The e2e tests won't pass in CI until https://gitlab.com/gitlab-org/gitter/webapp/-/issues/2495 is fixed (via https://gitlab.com/gitlab-org/gitter/webapp/-/merge_requests/1859)