server: reduce log spam on canceled batch requests

In #102793 we added server side logging for batch requests
that would encounted a context cancelation or timeout. This
was primarily motivated by the need to understand why export
requests sent during a backup were spending most of their time
and timing out. This unintentionally added log spam for other
kinds of internal requests such as HeartbeatTxn, QueryTxn,
and EndTxn requests. This change limits this log line to only
be printed when the corresponding request is an export request.

Fixes: None
Release note: None

pkg/server/node.go

@@ -1361,7 +1361,10 @@ func (n *Node) batchInternal(
 	// replica to notice the cancellation and return a response. For this reason,
 	// we log the server-side trace of the cancelled request to help debug what
 	// the request was doing at the time it noticed the cancellation.
-	if pErr != nil && ctx.Err() != nil {
+	//
+	// To avoid log spam for now we only log the trace if the request was an
+	// ExportRequest.
+	if pErr != nil && ctx.Err() != nil && args.IsSingleExportRequest() {
 		if sp := tracing.SpanFromContext(ctx); sp != nil && !sp.IsNoop() {
 			recording := sp.GetConfiguredRecording()
 			if recording.Len() != 0 {