runtime, cmd/trace: remove code paths that include v1 tracer
This change makes the new execution tracer described in #60773, the
default tracer. This change attempts to make the smallest amount of
changes for a single CL.
Updates #66703
For #60773
Change-Id: I3742f3419c54f07d7c020ae5e1c18d29d8bcae6d
Reviewed-on: https://go-review.googlesource.com/c/go/+/576256 Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>