Fix `Get-PACS-studies.py` / `Get-PACS-studies.sh`

[heyhaleema]

[vbutterworth]

Current code; Get-PACS-studies.py

1. Patient ID does not appear in .csv output. This is because it was calling "patientId" rather than "id".

I have made these changes, added my initial and date of change to the top and got the expected output for RT data from Aria (PACS ID 4).

Get-PACS-studies.py

[vbutterworth]

Additionally, either in the script itself or in the SOP to run the script, it needs to contain the reminder to delete the previous batch json files because it cannot write over them!