runtime/pprof: remove "deleted" suffix while parsing maps file

If binary file of a running program was deleted or moved, maps
file (/proc/pid/maps) will contain lines that have this binary
filename suffixed with "(deleted)" string. This suffix stayed
as a part of the filename and made remote profiling slightly more
difficult by requiring from a user to rename binary file to
include this suffix.

This change cleans up the filename and removes this suffix and
thus simplify debugging.

Fixes #25740

Change-Id: Ib3c8c3b9ef536c2ac037fcc14e8037fa5c960036
Reviewed-on: https://go-review.googlesource.com/116395


Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>