Bug: Fix RTT report when multiple servers are included

[boris-ilijic]

When executing RTT command for NATS cluster setup, RTT is probably not reported correctly for all servers within the cluster.

E.g. after the following command is executed:

n rtt -s tls://connect.ngs.global
tls://connect.ngs.global:

    tls://34.159.142.0:4222: 15.005017ms
   tls://34.89.235.191:4222: 13.955248ms
    tls://34.107.15.96:4222: 14.124726ms

each RTT reported above was measured for tls://connect.ngs.global host (which can be resolved to any IP above) and not for each specific IP listed above. So the report is misleading: it is correct for at least one IP, but probably not for all 3 of them.

This PR fixes that issue.

[boris-ilijic]

The result of this fix can be seen more clearly if we apply --trace switch from PR: #876 .

RTT for global.ngs.com without applied fix:

nats rtt --trace 2                                                                                                                                 on git:rtt-verbose-mode|⚑1 o
RTT iterations for server: tls://connect.ngs.global
#1:	rtt=15.779399ms
#2:	rtt=15.860255ms

RTT iterations for server: tls://connect.ngs.global
#1:	rtt=16.551375ms
#2:	rtt=15.209163ms

RTT iterations for server: tls://connect.ngs.global
#1:	rtt=16.335726ms
#2:	rtt=15.195447ms

tls://connect.ngs.global:

   tls://34.89.235.191:4222: 15.819827ms
    tls://34.159.142.0:4222: 15.880269ms
    tls://34.107.15.96:4222: 15.765586ms

RTT for global.ngs.com with the applied fix:

nats rtt --trace 2                                                                                                                                         on git:rtt-full|⚑1 o
RTT iterations for server: tls://34.89.235.191:4222
#1:	rtt=15.64317ms
#2:	rtt=16.001344ms

RTT iterations for server: tls://34.159.142.0:4222
#1:	rtt=17.582668ms
#2:	rtt=15.36456ms

RTT iterations for server: tls://34.107.15.96:4222
#1:	rtt=15.038285ms
#2:	rtt=15.837548ms

tls://connect.ngs.global:

   tls://34.89.235.191:4222: 15.822257ms
    tls://34.159.142.0:4222: 16.473614ms
    tls://34.107.15.96:4222: 15.437916ms

[ripienaar]

Nice thank you @boris-ilijic. Are you able to sign your commits? thank you!

[boris-ilijic]

@ripienaar Commit is signed