[MM-38579] Removing some town square permissions stuff (#18464)

* removing some town square permissions stuff

* fixing error

* adding back in channel leave check

* removing tests

Co-authored-by: Benjamin Cooke <benjamincooke@Benjamins-MacBook-Pro.local>

api4/post.go

@@ -713,13 +713,6 @@ func saveIsPinnedPost(c *Context, w http.ResponseWriter, isPinned bool) {
 		return
 	}
 
-	// Restrict pinning if the experimental read-only-town-square setting is on.
-	user, err := c.App.GetUser(c.AppContext.Session().UserId)
-	if err != nil {
-		c.Err = err
-		return
-	}
-
 	post, err := c.App.GetSinglePost(c.Params.PostId)
 	if err != nil {
 		c.Err = err
@@ -727,19 +720,6 @@ func saveIsPinnedPost(c *Context, w http.ResponseWriter, isPinned bool) {
 	}
 	auditRec.AddMeta("post", post)
 
-	channel, err := c.App.GetChannel(post.ChannelId)
-	if err != nil {
-		c.Err = err
-		return
-	}
-
-	if c.App.Srv().License() != nil &&
-		channel.Name == model.DefaultChannelName &&
-		!c.App.RolesGrantPermission(user.GetRoles(), model.PermissionManageSystem.Id) {
-		c.Err = model.NewAppError("saveIsPinnedPost", "api.post.save_is_pinned_post.town_square_read_only", nil, "", http.StatusForbidden)
-		return
-	}
-
 	patch := &model.PostPatch{}
 	patch.IsPinned = model.NewBool(isPinned)