This reverts commit 21bb43cc.

Reason for revert: See broken build: https://ci.chromium.org/p/v8/builders/ci/V8%20Linux64%20-%20builder/49882

Original change's description:
> [log][d8] Only use d8.log.getAndStop on temporary log file
> 
> We run tests in parallel which can cause multiple tests to write to
> the shared v8.log file. This obviously breaks the simple assertions in
> mjsunit/tools/log.js.
> 
> - Use temporary files for log testing with --logfile='+'
> 
> - Change the symbol from '&' to '+' for using temporary files for
>   logging with --logfile
> 
> - Enable skipped log tests again.
> 
> Bug: v8:10937, chromium:1129854, chromium:1130196
> Change-Id: I607dc9a9ecc352e58525cdd21c1c93efebf0f09f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2421826
> Commit-Queue: Camillo Bruni <cbruni@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Reviewed-by: Victor Gomes <victorgomes@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#70071}

TBR=cbruni@chromium.org,verwaest@chromium.org,victorgomes@chromium.org

Change-Id: I5de61792c283139b2a898334e28e1f7b2d7c08f8
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:10937
Bug: chromium:1129854
Bug: chromium:1130196
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2424625Reviewed-by: Francis McCabe <fgm@chromium.org>
Commit-Queue: Francis McCabe <fgm@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70072}