update(schemas): relax environment id requirement in service upgraded

Some CD tools (e.g. Spinnaker) have no concept of environment, forcing
producers to set id to a placeholder like "n/a". This change adds a
tier field with x-suggested-values (prod, nonprod, unknown) and relaxes
the constraint to require at least one of id or tier, so tools without
a meaningful environment id can use tier instead.

Signed-off-by: xibz <bjp@apple.com>

Author: xibz

schemas/serviceupgraded.json

@@ -70,6 +70,11 @@
                   "type": "string",
                   "minLength": 1
                 },
+                "tier": {
+                  "type": "string",
+                  "minLength": 1,
+                  "x-suggested-values": ["prod", "nonprod", "unknown"]
+                },
                 "source": {
                   "type": "string",
                   "minLength": 1,
@@ -78,8 +83,9 @@
               },
               "additionalProperties": false,
               "type": "object",
-              "required": [
-                "id"
+              "anyOf": [
+                {"required": ["id"]},
+                {"required": ["tier"]}
               ]
             },
             "artifactId": {