Security issue in the way tiled writer is used

Currently metadata data is added to the run metadata by blueapi [here](https://github.com/DiamondLightSource/blueapi/blob/be81937828bf7f143dcf20584002a5a126e83407/src/blueapi/service/interface.py#L163) , This is used by the TiledWriter [here](https://github.com/bluesky/bluesky/blob/fb2c3246676432c561ab733f6912135601c71d59/src/bluesky/callbacks/tiled_writer.py#L572)

This opens up a potential security vulnerability in which User A with permission to write to session 1 can write to all the sessions that the service_account has access to mid plan.