luci: use Python3 on LUCI am: 8d1f327ca3
luci: use Python3 on LUCI am: 8d1f327ca3

Original change: https://android-review.googlesource.com/c/platform/external/perfetto/+/2063850

Change-Id: I2442a07d058c0a5b0cf05bc10812f6f79cbafb19
Signed-off-by: Automerger Merge Worker <77fb6a4b42fa0ae17baba072a3edff99aa7eeb47@system.gserviceaccount.com>

google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto