Use longer timeouts in some legacy tests
Background
Some of our tests are timing out (e.g. https://gitlab.com/eyeo/adblockplus/adblockpluscore/-/jobs/491523897). The default timeout in Mocha is 2 seconds, but it can be changed at the suite level, the test level, and the hook level. For now, we can use longer timeouts for the legacy tests that are expected to take too long. In the long run, we should split up such tests (#87).
What to change
See !268 (closed).
Hints for testers
N/A
/cc @hfiguiere
Edited by Manish Jethani