[CT-1024] chore: update error endpoint

[Anne-ClaireFouchier]

• Remove error method for redact_request v4
• Change redact_job get_error() to return status error message

[Anne-ClaireFouchier]

Before the change, this is what calling get_error would return :

Traceback (most recent call last):
  File "/Users/anne-clairefouchier/debug/debug.py", line 34, in <module>
    main()
  File "/Users/anne-clairefouchier/debug/debug.py", line 23, in main
    print(f"error : {job.get_error()}")
  File "/Users/anne-clairefouchier/opt/miniconda3/lib/python3.9/site-packages/redact/v4/redact_job.py", line 63, in get_error
    return self.redact.get_error(
  File "/Users/anne-clairefouchier/opt/miniconda3/lib/python3.9/site-packages/redact/v4/redact_requests.py", line 289, in get_error
    raise RedactResponseError(response=response, msg="Error getting job error")
redact.errors.RedactResponseError: <Response [404 NOT FOUND]> Error getting job error

Now, we return a dictionary, as of example:

{'error': 'An unknown error has occurred. Please contact Brighter AI for support.'}