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>

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 {