ipn/ipnlocal, engine: avoid runtime/pprof with two usages of ts_omit_debug

Saves 258 KB.

Updates #12614

Change-Id: I37c2f7f916480e3534883f338de4c64d08f7ef2b
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Internal Server Error - Gitea: Git with a cup of tea
500 Internal Server Error

Gitea Version: 1.28.0+dev-477-g8b6ad49a5f