Revert "MM-55295: Improve DB performance of some APIs (#25318)" (#25852)

This reverts commit ec88ab4ee9.

server/channels/app/authorization.go

@@ -83,6 +83,7 @@ func (a *App) SessionHasPermissionToChannel(c request.CTX, session model.Session
 	}
 
 	ids, err := a.Srv().Store().Channel().GetAllChannelMembersForUser(session.UserId, true, true)
+
 	var channelRoles []string
 	if err == nil {
 		if roles, ok := ids[channelID]; ok {
@@ -259,22 +260,17 @@ func (a *App) HasPermissionToChannel(c request.CTX, askingUserId string, channel
 		return false
 	}
 
-	// We call GetAllChannelMembersForUser instead of just getting
-	// a single member from the DB, because it's cache backed
-	// and this is a very frequent call.
-	ids, err := a.Srv().Store().Channel().GetAllChannelMembersForUser(askingUserId, true, true)
-	var channelRoles []string
+	channelMember, err := a.GetChannelMember(c, channelID, askingUserId)
 	if err == nil {
-		if roles, ok := ids[channelID]; ok {
-			channelRoles = strings.Fields(roles)
-			if a.RolesGrantPermission(channelRoles, permission.Id) {
-				return true
-			}
+		roles := channelMember.GetRoles()
+		if a.RolesGrantPermission(roles, permission.Id) {
+			return true
 		}
 	}
 
-	channel, appErr := a.GetChannel(c, channelID)
-	if appErr == nil {
+	var channel *model.Channel
+	channel, err = a.GetChannel(c, channelID)
+	if err == nil {
 		return a.HasPermissionToTeam(c, askingUserId, channel.TeamId, permission)
 	}