[infra] No relative path for infra_tests.isolate

This should allow dependent repos to use their own version of this
isolate file.

Change-Id: I4afe08cc35da51f4bade0c4a80964dcece91bd8d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/226514
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
1 file changed