openapi: Rearrange users/{user_id}/subscriptions/{stream_id} docs.

This commit moves docs for users/{user_id}/subscriptions/{stream_id}
enndpoint to be after users/me/subscriptions/muted_topics docs.

We are rearranging the docs because after adding the new patch
endpoint for users/{user_id}/subscriptions/{stream_id}, openapi_core
validator tries to match 'users/me/subscriptions/muted_topics'
with 'users/{user_id}/subscriptions/{stream_id}' path in zulip.yaml
and thus gives error while running tests.

This is a bug in 'openapi_core' as it does not follows OpenAPI specs
to match concrete paths before their templated counterparts. Thus,
this commit rearranges the docs such that openapi_core validator
tries to match muted_topics endpoint with the correct path in
zulip.yaml docs.

zerver/openapi/zulip.yaml

@@ -4966,34 +4966,6 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/NonExistingStreamError"
-  /users/{user_id}/subscriptions/{stream_id}:
-    get:
-      operationId: get_subscription_status
-      tags: ["streams"]
-      description: |
-        Check whether a user is subscribed to a stream.
-
-        `GET {{ api_url }}/v1/users/{user_id}/subscriptions/{stream_id}`
-
-        **Changes**: New in Zulip 3.0 (feature level 11).
-      parameters:
-        - $ref: "#/components/parameters/UserId"
-        - $ref: "#/components/parameters/StreamIdInPath"
-      responses:
-        "200":
-          description: Success
-          content:
-            application/json:
-              schema:
-                allOf:
-                  - $ref: "#/components/schemas/JsonSuccess"
-                  - properties:
-                      is_subscribed:
-                        type: boolean
-                        description: |
-                          Whether the user is subscribed to the stream.
-                  - example:
-                      {"msg": "", "result": "success", "is_subscribed": false}
   /users/me/subscriptions/muted_topics:
     patch:
       operationId: mute_topic
@@ -5063,6 +5035,34 @@ paths:
                       - $ref: "#/components/schemas/JsonError"
                       - example:
                           {"msg": "Topic is not muted", "result": "error"}
+  /users/{user_id}/subscriptions/{stream_id}:
+    get:
+      operationId: get_subscription_status
+      tags: ["streams"]
+      description: |
+        Check whether a user is subscribed to a stream.
+
+        `GET {{ api_url }}/v1/users/{user_id}/subscriptions/{stream_id}`
+
+        **Changes**: New in Zulip 3.0 (feature level 11).
+      parameters:
+        - $ref: "#/components/parameters/UserId"
+        - $ref: "#/components/parameters/StreamIdInPath"
+      responses:
+        "200":
+          description: Success
+          content:
+            application/json:
+              schema:
+                allOf:
+                  - $ref: "#/components/schemas/JsonSuccess"
+                  - properties:
+                      is_subscribed:
+                        type: boolean
+                        description: |
+                          Whether the user is subscribed to the stream.
+                  - example:
+                      {"msg": "", "result": "success", "is_subscribed": false}
   /realm/emoji/{emoji_name}:
     post:
       operationId: upload_custom_emoji