Remove deprecated function (#27605)

* make /ancillary a post

* remove get from client, fix tests

* remove GET for retrieving ancillary permissions

* Update permissions.yaml

* Update permissions.yaml

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

api/v4/source/permissions.yaml

@@ -1,35 +1,4 @@
   /api/v4/permissions/ancillary:
-    get:
-      tags:
-        - permissions
-      summary: Return all system console subsection ancillary permissions
-      description: >
-        Returns all the ancillary permissions for the corresponding system console
-        subsection permissions appended to the requested permission subsections.
-
-
-        __Minimum server version__: 5.35
-      operationId: GetAncillaryPermissions
-      parameters:
-        - name: subsection_permissions
-          in: query
-          description: >
-            The subsection permissions to return the ancillary permissions for.
-            These values are comma seperated.
-            Ex. subsection_permissions=sysconsole_read_reporting_site_statistics,sysconsole_write_reporting_site_statistics,sysconsole_write_user_management_channels
-          schema:
-            type: string
-      responses:
-        "200":
-          description: Successfully returned all ancillary and requested permissions
-          content:
-            application/json:
-              schema:
-                type: array
-                items:
-                  type: string
-        "400":
-          $ref: '#/components/responses/BadRequest'
     post:
       tags:
         - permissions

server/channels/api4/permission.go

@@ -6,35 +6,14 @@ package api4
 import (
 	"encoding/json"
 	"net/http"
-	"strings"
 
 	"github.com/mattermost/mattermost/server/public/model"
 )
 
 func (api *API) InitPermissions() {
-	// to be deprecated - kept for backward compatibility
-	api.BaseRoutes.Permissions.Handle("/ancillary", api.APISessionRequired(appendAncillaryPermissions)).Methods(http.MethodGet)
 	api.BaseRoutes.Permissions.Handle("/ancillary", api.APISessionRequired(appendAncillaryPermissionsPost)).Methods(http.MethodPost)
 }
 
-func appendAncillaryPermissions(c *Context, w http.ResponseWriter, r *http.Request) {
-	keys, ok := r.URL.Query()["subsection_permissions"]
-
-	if !ok || len(keys[0]) < 1 {
-		c.SetInvalidURLParam("subsection_permissions")
-		return
-	}
-
-	permissions := strings.Split(keys[0], ",")
-	b, err := json.Marshal(model.AddAncillaryPermissions(permissions))
-	if err != nil {
-		c.SetJSONEncodingError(err)
-		return
-	}
-
-	w.Write(b)
-}
-
 func appendAncillaryPermissionsPost(c *Context, w http.ResponseWriter, r *http.Request) {
 	permissions, err := model.NonSortedArrayFromJSON(r.Body)
 	if err != nil || len(permissions) < 1 {