Remove migrated integrations from plugin manifest

This change removes Scaleway and Mondoo from the external plugins manifest in favor
of the integration framework, which they have migrated to.

website/data/plugins-manifest.json

@@ -52,13 +52,6 @@
     "pluginTier": "community",
     "version": "latest"
   },
-  {
-    "title": "Mondoo",
-    "path": "mondoo",
-    "repo": "mondoohq/packer-plugin-mondoo",
-    "pluginTier": "verified",
-    "version": "latest"
-  },
   {
     "title": "Nutanix",
     "path": "nutanix",
@@ -75,13 +68,6 @@
     "pluginTier": "verified",
     "isHcpPackerReady": true
   },
-  {
-    "title": "Scaleway",
-    "path": "scaleway",
-    "repo": "scaleway/packer-plugin-scaleway",
-    "pluginTier": "verified",
-    "version": "latest"
-  },
   {
     "title": "UCloud",
     "path": "ucloud",