Merge "Add "thread" label to pprof_proto_generator" am: 078d73d307 am: 9ad241b6d8 am: b9141f8e32

Original change: https://android-review.googlesource.com/c/platform/system/extras/+/1806503

Change-Id: I16294219ad3fac705453f28089d01ff5f658fbcd