SKA: Flag @kbn/observability-synthetics-test-data as devOnly (elast…

…ic#209252)

## Summary

This package relies on devOnly packages, thus it must be devOnly too.

---------

Co-authored-by: kibanamachine <42973632+kibanamachine@users.noreply.github.com>

package.json

@@ -709,7 +709,6 @@
     "@kbn/observability-onboarding-plugin": "link:x-pack/solutions/observability/plugins/observability_onboarding",
     "@kbn/observability-plugin": "link:x-pack/solutions/observability/plugins/observability",
     "@kbn/observability-shared-plugin": "link:x-pack/solutions/observability/plugins/observability_shared",
-    "@kbn/observability-synthetics-test-data": "link:x-pack/solutions/observability/packages/synthetics_test_data",
     "@kbn/observability-utils-browser": "link:x-pack/solutions/observability/packages/utils_browser",
     "@kbn/observability-utils-common": "link:x-pack/solutions/observability/packages/utils_common",
     "@kbn/observability-utils-server": "link:x-pack/solutions/observability/packages/utils_server",
@@ -1469,6 +1468,7 @@
     "@kbn/manifest": "link:packages/kbn-manifest",
     "@kbn/mock-idp-plugin": "link:packages/kbn-mock-idp-plugin",
     "@kbn/mock-idp-utils": "link:packages/kbn-mock-idp-utils",
+    "@kbn/observability-synthetics-test-data": "link:x-pack/solutions/observability/packages/synthetics_test_data",
     "@kbn/openapi-bundler": "link:packages/kbn-openapi-bundler",
     "@kbn/openapi-generator": "link:packages/kbn-openapi-generator",
     "@kbn/optimizer": "link:packages/kbn-optimizer",

x-pack/solutions/observability/packages/synthetics_test_data/kibana.jsonc

@@ -3,5 +3,6 @@
   "id": "@kbn/observability-synthetics-test-data",
   "owner": "@elastic/obs-ux-management-team",
   "group": "observability",
-  "visibility": "private"
+  "visibility": "private",
+  "devOnly": true
 }