runtime: remove implicit NOFRAME heuristic support

runtime: remove implicit NOFRAME heuristic support

All amd64 OSes already make use of the NOFRAME flag wherever is
required, so we can remove the frameless nosplit functions heuristic
code path.

Updates #58378

Change-Id: I966970693ba07f8c66da0aca83c23caad7cbbfe5
Reviewed-on: https://go-review.googlesource.com/c/go/+/466458
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Quim Muntal <quimmuntal@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>