Revert "Adding caching to get channel member (#5518)"

This reverts commit ba028ed74b.

store/store.go

@@ -106,8 +106,7 @@ type ChannelStore interface {
 	SaveMember(member *model.ChannelMember) StoreChannel
 	UpdateMember(member *model.ChannelMember) StoreChannel
 	GetMembers(channelId string, offset, limit int) StoreChannel
-	GetMember(channelId string, userId string, allowFromCache bool) StoreChannel
-	InvalidateMember(channelId string, userId string)
+	GetMember(channelId string, userId string) StoreChannel
 	GetAllChannelMembersForUser(userId string, allowFromCache bool) StoreChannel
 	InvalidateAllChannelMembersForUser(userId string)
 	IsUserInChannelUseCache(userId string, channelId string) bool