This modernizes python code without breaking Py2 compat.

Ran with command:

futurize --stage1 -w predictable_wrapper.py
futurize --stage1 -w run-num-fuzzer.py
futurize --stage1 -w run-tests.py
futurize --stage1 -w v8_presubmit.py

This only adds the absolute import, which use these semantics. It
doesn't do anything differently in our case, these scripts are already
doing absolute imports. But with these changes, running `futurize
--stage2` will be less messy.

Bug: v8:9871
Change-Id: I28182ab73dac6cfcbd544c2046026f14e5157eb3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2252555Reviewed-by: Tamer Tas <tmrts@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68588}