Improve reliability of QA tests

Created by: slimsag

Today we have "e2e regression" tests at https://sourcegraph.com/github.com/sourcegraph/sourcegraph/-/blob/web/src/regression/README.md which perform a number of QA tests.

We cannot release without these passing, yet a majority of the time these are failing by the end of the iteration.

This is a tracking issue for us to improve the reliability of them. We should identify ways to make certain they are reliable, even if it means they run slowly and e.g. have long sleep statements between steps.

This is a broad issue because the problem is broad - there are a lot of tests and this will need to be done on a case-by-case basis. This is a tracking issue for that work, which should be linked as an issue below:

• https://github.com/sourcegraph/sourcegraph/issues/14874
• [] TODO: link to other issues about improving reliability here.