e2e: sort symbols list to avoid flakiness
Created by: sqs
The symbols e2e test had flakiness at https://buildkite.com/sourcegraph/sourcegraph-e2e/builds/1755#86f72961-3331-4c82-834b-6ced0cbe290d/154-681. This sorts the list to avoid the flakiness. Because the symbols order is not strictly defined anyway, sorting does not make the test any less effective.