auxiliary processes in pg_stat_ssl

I just noticed that we list auxiliary processes in pg_stat_ssl:

55432 13devel 28627=# select * from pg_stat_ssl ;
  pid  │ ssl │ version │         cipher         │ bits │ compression │ client_dn │ client_serial │ issuer_dn 
───────┼─────┼─────────┼────────────────────────┼──────┼─────────────┼───────────┼───────────────┼───────────
 28618 │ f   │         │                        │      │             │           │               │ 
 28620 │ f   │         │                        │      │             │           │               │ 
 28627 │ t   │ TLSv1.3 │ TLS_AES_256_GCM_SHA384 │  256 │ f           │           │               │ 
 28616 │ f   │         │                        │      │             │           │               │ 
 28615 │ f   │         │                        │      │             │           │               │ 
 28617 │ f   │         │                        │      │             │           │               │ 
(6 filas)

55432 13devel 28627=# select pid, backend_type from pg_stat_activity ;
  pid  │         backend_type         
───────┼──────────────────────────────
 28618 │ autovacuum launcher
 28620 │ logical replication launcher
 28627 │ client backend
 28616 │ background writer
 28615 │ checkpointer
 28617 │ walwriter
(6 filas)

But this seems pointless.  Should we not hide those?  Seems this only
happened as an unintended side-effect of fc70a4b0df38.  It appears to me
that we should redefine that view to restrict backend_type that's
'client backend' (maybe include 'wal receiver'/'wal sender' also, not
sure.)

-- 
Álvaro Herrera                                http://www.twitter.com/alvherre