Remove guard for initial notifications

[fgalan]

Initial notifications are going to be deprecated in Orion Context Broker. They are being deprecated in Orion 3.1.0 and the removal is expected for 3.2.0.

When that moment comes, the Perseo FE guard code to "protect" against initial notification will no be longer needed.

Maybe this trace (generated by Perseo when some initial notification is received) may help:

time=2021-05-21T09:02:02.557Z | lvl=INFO | corr=353ab12e-ba13-11eb-a5eb-0242ac110011; node=Y6jsj505U; perseocep=206 | trans=9b50a50e-97f2-4748-9d3a-a754be349a5e | op=/notices | path=/notices | comp=perseo-fe | srv=smartcity | subsrv=/ | from=::ffff:172.17.0.17 | msg=sending response: 400 {"error":"Number of servicepath items does not match ContextResponses(1,2)","data":null}

[fgalan]

Similar to issue telefonicaid/fiware-cygnus#2044

[AlvaroVega]

perseo-fe/lib/models/notices.js

Lines 382 to 383 in 1f3c70c

	if (orionResponse.length !== sps.length) {
	return callback(new errors.ServipathCountMismatch('(' + sps.length + ',' + orionResponse.length + ')'));