Cluster Count is off by one in the dashboards

[ColinSullivan1]

What version were you using?

Surveyor 0.9.3.
Server version 2.12.0-dev

What environment was the server running in?

Servers on MacOSx, surveyor, prometheus, and grafana in docker.

Is this defect reproducible?

Yes. Launch a supercluster and observe the cluster counts in the cluster and supercluster dashboards.

Given the capability you are leveraging, describe your expectation?

That the count is accurate.

Given the expectation, what is the defect you are observing?

I have a supercluster of 3 clusters, however in the Cluster and SuperCluster dashboards, the cluster count is reporting 2, which is not accurate.

Results from nats server report health

$ ./nats_sys server report health
╭───────────────────────────────────────────────────────────╮
│                       Health Report                       │
├────────┬─────────┬────────┬────────────────┬──────┬───────┤
│ Server │ Cluster │ Domain │ Status         │ Type │ Error │
├────────┼─────────┼────────┼────────────────┼──────┼───────┤
│ r1_a   │ region1 │        │ ok (200)       │      │       │
│ r1_b   │ region1 │        │ ok (200)       │      │       │
│ r1_c   │ region1 │        │ ok (200)       │      │       │
│ r2_a   │ region2 │        │ ok (200)       │      │       │
│ r2_b   │ region2 │        │ ok (200)       │      │       │
│ r2_c   │ region2 │        │ ok (200)       │      │       │
│ r3_a   │ region3 │        │ ok (200)       │      │       │
│ r3_b   │ region3 │        │ ok (200)       │      │       │
│ r3_c   │ region3 │        │ ok (200)       │      │       │
├────────┼─────────┼────────┼────────────────┼──────┼───────┤
│ 9      │ 3       │        │ ok: 9 / err: 0 │      │     0 │
╰────────┴─────────┴────────┴────────────────┴──────┴───────╯

Three clusters are reported in the NATS cli summary.

On the same cluster, using the dashboard a count of 2 is reported in the supercluster dashboard, when all are reported in the metric details:

The same goes for the cluster dashboard:

Note: With a single cluster (no gateways), the dashboards display 0.

I'm thinking the metrics pertaining to cluster count should be max(nats_core_gateway_count)+1 wdyt?

Happy to submit a PR, let me know.