pkg/*: Tag all support metrics with metricVisibility label

This commit modifies the visibility of numerous metrics throughout the codebase, setting them to SUPPORT. This change enhances the clarity of metric categorization and ensures consistent visibility handling across different modules, including metrics related to changefeeds, transactions, and system performance.

Part of: CRDB-57282
Epic: CRDB-55082
Release note: None

Author: Abhinav1299

docs/generated/metrics/metrics.yaml

@@ -970,6 +970,7 @@ func newAggregateMetrics(histogramWindow time.Duration, lookup *cidr.Lookup) *Ag
 		Help:        "Number of changefeeds currently executing backfill",
 		Measurement: "Count",
 		Unit:        metric.Unit_COUNT,
+		Visibility:  metric.Metadata_SUPPORT,
 	}
 	metaChangefeedBackfillPendingRanges := metric.Metadata{
 		Name:        "changefeed.backfill_pending_ranges",
@@ -1119,6 +1120,7 @@ func newAggregateMetrics(histogramWindow time.Duration, lookup *cidr.Lookup) *Ag
 		Help:        "The most any changefeed's persisted checkpoint is behind the present",
 		Measurement: "Nanoseconds",
 		Unit:        metric.Unit_NANOSECONDS,
+		Visibility:  metric.Metadata_SUPPORT,
 	}
 	metaChangefeedSpanProgressSkew := metric.Metadata{
 		Name:        "changefeed.progress_skew.span",

pkg/ccl/changefeedccl/metrics.go

@@ -216,6 +216,7 @@ var (
 		Help:        "Number of restarted KV transactions",
 		Measurement: "KV Transactions",
 		Unit:        metric.Unit_COUNT,
+		Visibility:  metric.Metadata_SUPPORT,
 	}
 	// There are two ways we can get "write too old" restarts. In both cases, a
 	// WriteTooOldError is generated in the MVCC layer. This is intercepted on

pkg/kv/kvclient/kvcoord/txn_metrics.go

@@ -179,6 +179,7 @@ var (
 		Help:        "Number of failed node liveness heartbeats from this node",
 		Measurement: "Messages",
 		Unit:        metric.Unit_COUNT,
+		Visibility:  metric.Metadata_SUPPORT,
 	}
 	metaEpochIncrements = metric.Metadata{
 		Name:        "liveness.epochincrements",