TemplateTool: upgrader first removes deprecated BT and then upgrade all BT

For example, if property_sheet "prop" was moved from BT 1 to BT 2 and BT 1 doesn't exist anymore.

Before this commit we have this order:

1. install BT 2 ("prop" exist and isn't touched)
2. remove BT 1 ("prop" is removed) => at the end "prop" doesn't exist anymore

After this commit we have this order:

1. remove BT 1 ("prop" is removed)
2. install BT 2 ("prop" is readded) => at the end "prop" exists and is OK

/cc @Nicolas @georgios.dagkakis @jerome @rafael