[9.1] [APM] Make captureHeaders: false default config (#239082) (#239120)

# Backport

This will backport the following commits from `main` to `9.1`:
- [[APM] Make `captureHeaders: false` default config
(#239082)](#239082)

<!--- Backport version: 9.6.6 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

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Make `captureHeaders: false` default config
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Make `captureHeaders: false` default
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BACKPORT-->

Co-authored-by: Jean-Louis Leysens <[email protected]>

Author: kibanamachine

src/platform/packages/private/kbn-apm-config-loader/src/config.test.ts

@@ -88,6 +88,7 @@ describe('ApmConfiguration', () => {
       Object {
         "active": true,
         "breakdownMetrics": true,
+        "captureHeaders": false,
         "captureSpanStackTraces": false,
         "centralConfig": false,
         "contextPropagationOnly": true,

src/platform/packages/private/kbn-apm-config-loader/src/config.ts

@@ -21,6 +21,7 @@ import type { ApmConfigSchema } from './apm_config';
 // https://www.elastic.co/guide/en/apm/agent/nodejs/current/configuration.html
 const DEFAULT_CONFIG: AgentConfigOptions = {
   active: true,
+  captureHeaders: false,
   contextPropagationOnly: true,
   environment: 'development',
   globalLabels: {},
@@ -47,7 +48,6 @@ export const CENTRALIZED_SERVICE_BASE_CONFIG: AgentConfigOptions | RUMAgentConfi
 const CENTRALIZED_SERVICE_DIST_CONFIG: AgentConfigOptions = {
   breakdownMetrics: false,
   captureBody: 'off',
-  captureHeaders: false,
   metricsInterval: '120s',
   transactionSampleRate: 0.1,
 };