[exporter/clickhouse] Use the standard default of 10 queue consumers (#34176)

**Description:** 
The default number of [queue consumers is in the exporter helper
10](https://github.com/open-telemetry/opentelemetry-collector/blob/main/exporter/exporterhelper/queue_sender.go#L45).
This default is respected by every other exporter in this repo except
for the ClickHouse exporter. A default of 1 is way too low for any major
workload and adds a low ceiling to the vertical scalability of a single
collector.

**Link to tracking Issue:** n/a

**Testing:** n/a

**Documentation:** Added the default values to the README

Author: tommyzli

.chloggen/clickhouse-default-consumer-concurrency.yaml

@@ -0,0 +1,27 @@
+# Use this changelog template to create an entry for release notes.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: bug_fix
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: clickhouseexporter
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Increase the default number of queue consumers to 10
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: [34176]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:
+
+# If your change doesn't affect end users or the exported elements of any package,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+# Optional: The change log or logs in which this entry should be included.
+# e.g. '[user]' or '[user, api]'
+# Include 'user' if the change is relevant to end users.
+# Include 'api' if there is a change to a library API.
+# Default: '[user]'
+change_logs: []

exporter/clickhouseexporter/README.md

@@ -312,6 +312,8 @@ Processing:
 
 - `timeout` (default = 5s): The timeout for every attempt to send data to the backend.
 - `sending_queue`
+    - `enabled` (default = true)
+    - `num_consumers` (default = 10): Number of consumers that dequeue batches; ignored if `enabled` is `false`
     - `queue_size` (default = 1000): Maximum number of batches kept in memory before dropping data.
 - `retry_on_failure`
     - `enabled` (default = true)

exporter/clickhouseexporter/config_test.go

@@ -70,7 +70,7 @@ func TestLoadConfig(t *testing.T) {
 				ConnectionParams: map[string]string{},
 				QueueSettings: exporterhelper.QueueSettings{
 					Enabled:      true,
-					NumConsumers: 1,
+					NumConsumers: 10,
 					QueueSize:    100,
 					StorageID:    &storageID,
 				},

exporter/clickhouseexporter/factory.go

@@ -30,12 +30,9 @@ func NewFactory() exporter.Factory {
 }
 
 func createDefaultConfig() component.Config {
-	queueSettings := exporterhelper.NewDefaultQueueSettings()
-	queueSettings.NumConsumers = 1
-
 	return &Config{
 		TimeoutSettings:  exporterhelper.NewDefaultTimeoutSettings(),
-		QueueSettings:    queueSettings,
+		QueueSettings:    exporterhelper.NewDefaultQueueSettings(),
 		BackOffConfig:    configretry.NewDefaultBackOffConfig(),
 		ConnectionParams: map[string]string{},
 		Database:         defaultDatabase,