Surprisingly long jank marker when the event delay track doesn't show anything unusual

This profile has a jank marker with a surprisingly long duration: https://share.firefox.dev/3iXI9Xt

Nazim's comment on it: " I don't see the same thing in the event delays chart. but that can be because of the graph issue actually. I think we ignore the first event delay number for the chart because it's mostly not reliable (and it looks like this jank marker is the first event delay in the thread) It can be either with the graph or marker to blame :confused:"

┆Issue is synchronized with this [Jira Task](https://mozilla-hub.atlassian.net/browse/FP-300)