Improve stability of e2e tests

[kraleppa]

We have some flaky e2e tests that sometimes breaks our CI pipelines - the goal of this task is to identify and fix them

[hhubert6]

One of very frequently occurring flakes is this fragment of test/e2e/dead_live_views_test.exs

debugger
|> visit("/")
|> assert_has(enable_dead_liveviews_checkbox(selected: false))
|> refute_has(css("#dead-sessions"))
|> click(enable_dead_liveviews_toggle())
|> find(css("#dead-sessions"))
|> assert_text("No dead LiveViews")

For the time being it's been commented in #819. It should be solved in the future.