[grit] Improve readability of pak file error

This CL removes the expected and actual lists of pak files from the
grit error message that is printed when the two lists do not match.

These lists are very long and not useful for debugging pak output
errors.  The error message already includes the missing, extra, and
duplicate pak files which are the actual issue that needs to be
addressed and usually a much shorter list.

Bug: 1293908
Change-Id: Id381834a1349689c3de356c377e53309ce2d8021
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3498909
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Commit-Queue: Trevor Perrier <perrier@chromium.org>
Cr-Commit-Position: refs/heads/main@{#976923}