Traces: Switch to regex for power rails The rails have been rearranged on some devices. Update the way we scan for output to find them in either case. Bug: angleproject:354006406 Change-Id: Ia3999fc2c07a726f4832e451af93a40949f87335 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/5722949 Reviewed-by: Roman Lavrov <romanl@google.com> Commit-Queue: Cody Northrop <cnorthrop@google.com>