The lists of tests can't be added to the sheets if more than 50,000
lines. Since the goal is to get rid of all unexpected passes/failures,
it's reasonable to clip the lists by length. Other formatting changes
too.

Bug: angleproject:3398
Change-Id: Ice461862fb4266e0ad1280f20de85224fc6d7e97
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1585612Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>