I/O is quite expensive on the bots. This cuts down a bit of it by
printing slightly fewer characters per test in verbose mode.

This leads to an overall speed improvement of ~20% for large test
suites, e.g. Test262 output-collection time goes from ~2m30 to ~2m.

The averages to a 5-10% overall speed improvement for slow tryjobs.

Bug: v8:10916
Change-Id: I56dcb072af8eb32a1e09e17a05db5782c6d79315
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2414038
Auto-Submit: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69950}