Revert "runtime: normalize sigprof traceback flags"

This reverts commit CL 358900.

Adding _TraceJumpStack to cgo traceback exposed a crashing condition.
This CL was primarily a cleanup, so we revert it entirely for now
and follow-up with the VDSO and libcall parts later.

Fixes #50936.

Change-Id: Ie45c9caaa8e2ef5bc9498ba65c36c887ca821bf7
Reviewed-on: https://go-review.googlesource.com/c/go/+/382079


Reviewed-by: Cherry Mui <cherryyz@google.com>
Trust: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>