net: Kconfig: discourage drop_monitor enablement

net: Kconfig: discourage drop_monitor enablement

Quoting Eric Dumazet:
"I do not understand the fascination with net/core/drop_monitor.c [..]
misses all the features, flexibility, scalability  that 'perf',
eBPF tracing, bpftrace, .... have today."

Reword DROP_MONITOR kconfig help text to clearly state that its not
related to perf-based drop monitoring and that its safe to disable
this unless support for the older netlink-based tools is needed.

Signed-off-by: Florian Westphal <fw@strlen.de>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20251016115147.18503-1-fw@strlen.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>