Six modules take their secrets from files; the rest say precisely why not

From the survey of every env-file secret (ADR 0086, issue 041): amqp-ping,
minio, mongodb and grafana use the _FILE twin their software honours;
mesh-catalog and model-usage read DATABASE_URL_FILE (a file the mesh
templates, mounted where only the runtime reads it); grafana's secret files
belong to its own account. Two dead deliveries removed: a line nothing read
in amqp-email-forwarder, and mailu's secret.env on four containers that
never read it. The 25 exceptions that remain carry the surveyed reason —
convertible and awaiting a bed, convertible through a generated config file,
the application's own code, or not convertible.

modules/mongodb/module.json

@@ -60,13 +60,6 @@
       "path": "/var/lib/mongodb/grants",
       "mode": "0700"
     },
-    {
-      "id": "root-env",
-      "type": "file",
-      "path": "/var/lib/mongodb/root.env",
-      "mode": "0600",
-      "content": "MONGO_INITDB_ROOT_PASSWORD=${secret:root}\n"
-    },
     {
       "id": "data",
       "type": "directory",
@@ -85,18 +78,16 @@
       "image": "mongo@sha256:e3fa459b4f4b72f3257c67a23c145e250b8b5700f033860392c68539b998bbe3",
       "network": "mongodb",
       "env": {
-        "MONGO_INITDB_ROOT_USERNAME": "root"
+        "MONGO_INITDB_ROOT_USERNAME": "root",
+        "MONGO_INITDB_ROOT_PASSWORD_FILE": "/run/secrets/root"
       },
-      "env-file": [
-        "/var/lib/mongodb/root.env"
-      ],
       "ports": [
         "27017"
       ],
       "volumes": [
-        "/services/mongodb/db-data:/data/db"
-      ],
-      "secrets-in-environment": "the image reads its configuration from the environment only; converting to a file is the per-module work of issue 041"
+        "/services/mongodb/db-data:/data/db",
+        "/var/lib/mongodb/root.secret:/run/secrets/root:ro"
+      ]
     },
     {
       "id": "runtime",