[APM] enable 'sanitize_field_names' for Go

elastic/apm-agent-go#856 added
central config support for 'sanitize_field_names' to the
Go agent, so we can now enable it in the UI too.

x-pack/plugins/apm/common/agent_configuration/setting_definitions/general_settings.ts

@@ -235,7 +235,7 @@ export const generalSettings: RawSettingDefinition[] = [
           'Sometimes it is necessary to sanitize, i.e., remove, sensitive data sent to Elastic APM. This config accepts a list of wildcard patterns of field names which should be sanitized. These apply to HTTP headers (including cookies) and `application/x-www-form-urlencoded` data (POST form fields). The query string and the captured request body (such as `application/json` data) will not get sanitized.',
       }
     ),
-    includeAgents: ['java', 'python'],
+    includeAgents: ['java', 'python', 'go'],
   },
 
   // Ignore transactions based on URLs

x-pack/plugins/apm/common/agent_configuration/setting_definitions/index.test.ts

@@ -46,6 +46,7 @@ describe('filterByAgent', () => {
         'capture_body',
         'capture_headers',
         'recording',
+        'sanitize_field_names',
         'span_frames_min_duration',
         'stack_trace_limit',
         'transaction_max_spans',