Collect built-in LWLock tranche names statically, not dynamically.

There is little point in using the LWLockRegisterTranche mechanism for
built-in tranche names.  It wastes cycles, it creates opportunities for
bugs (since failing to register a tranche name is a very hard-to-detect
problem), and the lack of any centralized list of names encourages
sloppy nonconformity in name choices.  Moreover, since we have a
centralized list of the tranches anyway in enum BuiltinTrancheIds, we're
certainly not buying any flexibility in return for these disadvantages.

Hence, nuke all the backend-internal LWLockRegisterTranche calls,
and instead provide a const array of the builtin tranche names.

(I have in mind to change a bunch of these names shortly, but this
patch is just about getting them into one place.)

Discussion: https://postgr.es/m/9056.1589419765@sss.pgh.pa.us

src/backend/replication/logical/origin.c

@@ -517,9 +517,6 @@ ReplicationOriginShmemInit(void)
 			ConditionVariableInit(&replication_states[i].origin_cv);
 		}
 	}
-
-	LWLockRegisterTranche(replication_states_ctl->tranche_id,
-						  "replication_origin");
 }
 
 /* ---------------------------------------------------------------------------

src/backend/replication/slot.c

@@ -140,9 +140,6 @@ ReplicationSlotsShmemInit(void)
 		ShmemInitStruct("ReplicationSlot Ctl", ReplicationSlotsShmemSize(),
 						&found);
 
-	LWLockRegisterTranche(LWTRANCHE_REPLICATION_SLOT_IO_IN_PROGRESS,
-						  "replication_slot_io");
-
 	if (!found)
 	{
 		int			i;