Most test-log tests create their own isolates, so initializing the cctest
isolate is not necessary.

Bug: v8:7464
Change-Id: Icc3cd9d5053c4070833709cbe28e5bde2cee9708
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1507719Reviewed-by: Dan Elphick <delphick@chromium.org>
Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
Cr-Commit-Position: refs/heads/master@{#60093}