fix(telemetry): state the real noun in sync-health rate units

Grafana renders `unit: "ops"` as the literal string "ops/s" and `cps`
as "counts/s", so seven rate panels on this dashboard read as
"operations per second" regardless of what they counted -- nodes added
to a SHAMap, dial attempts, ledger-data requests served.

Replace them with custom-suffix units naming the quantity, following
the `suffix:/hr` and `si:drops` precedent already in this repo. Each
noun was checked against the emitting code rather than the panel title:
sync_addnode_total counts SHAMap nodes, peer.dial spans are connect
attempts, ledger.serve spans are peer requests.

Also spell out "Ops / Sec" as "Operations / Sec" on the NodeStore panel,
since abbreviating the noun defeats the point of naming it.

Queries are unchanged; the values were already correct.

docker/telemetry/grafana/dashboards/ledger-sync-health.json

@@ -2118,7 +2118,7 @@
               }
             ]
           },
-          "unit": "ops"
+          "unit": "suffix: nodes/s"
         }
       },
       "gridPos": {
@@ -3662,7 +3662,7 @@
             "axisBorderShow": false,
             "axisCenteredZero": false,
             "axisColorMode": "text",
-            "axisLabel": "Ops / Sec",
+            "axisLabel": "Operations / Sec",
             "axisPlacement": "auto",
             "barAlignment": 0,
             "barWidthFactor": 0.6,
@@ -3702,7 +3702,7 @@
               }
             ]
           },
-          "unit": "ops"
+          "unit": "suffix: operations/s"
         }
       },
       "gridPos": {
@@ -4174,7 +4174,7 @@
               },
               {
                 "id": "unit",
-                "value": "cps"
+                "value": "suffix: writes/s"
               },
               {
                 "id": "custom.axisLabel",
@@ -4556,7 +4556,7 @@
               }
             ]
           },
-          "unit": "ops"
+          "unit": "suffix: acquisitions/s"
         }
       },
       "gridPos": {
@@ -4754,7 +4754,7 @@
               }
             ]
           },
-          "unit": "ops"
+          "unit": "suffix: dials/s"
         }
       },
       "gridPos": {
@@ -4853,7 +4853,7 @@
               }
             ]
           },
-          "unit": "ops"
+          "unit": "suffix: requests/s"
         }
       },
       "gridPos": {
@@ -4952,7 +4952,7 @@
               }
             ]
           },
-          "unit": "ops"
+          "unit": "suffix: validations/s"
         },
         "overrides": []
       },