Add option to remove the Trigger (pre-) Tag after processing

[DerTiger1]

Could you please add an option to remove the pre-tag after processing of the document.
I use it as trigger from paperless for new documents and also to re-tag.

[DerTiger1]

@clusterzx

[jlacour-git]

Just as an idea: I solved this by having a tag „ai-done“ added by paperless-ai, and creating an action in paperless-ngx that gets triggered by doc update and removes the trigger tag if the document also has the „ai-done“ tag.