_scan_gateway_pids() uses ps-based pattern matching to find running
gateways. When invoked from the CLI (e.g. `hermes gateway status`),
the calling process itself matches gateway patterns, causing false
positives — the CLI is mistakenly counted as a running gateway.
Add _get_ancestor_pids() that walks the process tree from the current
PID up to init (PID 1). Merge this set into exclude_pids at the top
of _scan_gateway_pids() so the entire ancestor chain is filtered out.
This complements the existing os.getpid() exclusion in
_append_unique_pid() by also covering parent/grandparent processes
(e.g. when hermes is invoked via a wrapper script or shell).
Closes#13242
Byrn Tong
e8cdcf5328