regression e2e: test fixes 3.15

Created by: uwedeportivo

can you guys go over these test edits and look if they're correct. even with these edits i get 5 failures for

SLOWMO=10 KEEP_BROWSER=true yarn run test:regression:search

run the instance like so:

IMAGE=sourcegraph/server:3.15.0-rc.3 ./dev/run-server-image.sh

and make yourself a .envrc before you run the tests as described here: ( you need at least a sourcegraph sudo token, a github token etc, change the sourcegraph base url to your setup)

Follow README.md to set up your e2e environment. Run the tests from the web directory. A more complete set of env vars can be found in this 1password entry.