Reland "Spawn isolates using platform kernel when using old ABIs"

This reverts commit 2a8117c341009cfaaf150701051f025d90086fb5.

Reason for revert: I think it was actually https://dart-review.googlesource.com/c/sdk/+/98609 that caused the breakage

Original change's description:
> Revert "Spawn isolates using platform kernel when using old ABIs"
> 
> This reverts commit c3113b0818d911500fef803202c5dea5012a171d.
> 
> Reason for revert: Broke some tests, eg https://logs.chromium.org/logs/dart/buildbucket/cr-buildbucket.appspot.com/8917089062837512336/+/steps/test_results/0/logs/tests_that_began_failing__logs_/0
> 
> Original change's description:
> > Spawn isolates using platform kernel when using old ABIs
> > 
> > Bug: https://github.com/dart-lang/sdk/issues/36047
> > Change-Id: I4a95ec336e1ba6b955563cca5498a18310b51379
> > Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/98260
> > Reviewed-by: Siva Annamalai <asiva@google.com>
> > Commit-Queue: Liam Appelbe <liama@google.com>
> 
> TBR=asiva@google.com,liama@google.com
> 
> Change-Id: I33a714add2858752015dec38b8d973347a3ba79a
> No-Presubmit: true
> No-Tree-Checks: true
> No-Try: true
> Bug: https://github.com/dart-lang/sdk/issues/36047
> Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/98684
> Reviewed-by: Liam Appelbe <liama@google.com>
> Commit-Queue: Liam Appelbe <liama@google.com>

TBR=asiva@google.com,liama@google.com

Change-Id: I8ce6b050f0c3aeb7ac4f15b83bbec0b3b0e909bd
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: https://github.com/dart-lang/sdk/issues/36047
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/98688
Reviewed-by: Liam Appelbe <liama@google.com>
Commit-Queue: Liam Appelbe <liama@google.com>