step-ca: stop offering acme-ca, so public names are certified by public-acme

step-ca and public-acme both offered acme-ca on novox, and route-proxy's pin names a node, not
a module — so which one certified the public names depended on provider order. After the
controller restart on 2026-10-03 it came out as step-ca, and every public site served a
certificate no browser trusts. step-ca's own names are already certified through
internal-acme-ca; acme-ca is the public authority's alone.

modules/step-ca/module.json

@@ -5,20 +5,12 @@
     "container-runtime"
   ],
   "provides": [
-    {
-      "name": "acme-ca",
-      "scope": "mesh"
-    },
     {
       "name": "internal-acme-ca",
       "scope": "mesh"
     }
   ],
   "serves": {
-    "acme-ca": {
-      "path": "/acme/acme/directory",
-      "roots": "/roots.pem"
-    },
     "internal-acme-ca": {
       "path": "/acme/acme/directory",
       "roots": "/roots.pem"