Update codecov tolerance and notification time

[CasperWA]

Unfortunately codecov is complaining, no idea why.

Is there a way that we can put a bigger tolerance to prevent these false positives? It is a bit annoying to have build officially fail just because a false positive in the coverage. Not only do PRs look like they are failing, even though everything is fine, but even when merging, it could mark the develop or master branch as failing, which will even influence the build status badge on the README in a negative way. Having a failing build status badge because of this is not the nicest. I have no experience with these coverage tools, so thought I'd ask before starting to investigate. @CasperWA do you have an idea?

Originally posted by @sphuber in #3957 (comment)

The coverage reporting should be a bit more friendly.