BeamlinePrefix does not support branch beamlines (e.g. i13-1 does not resolve to BL13J)

[DiamondJoseph]

get_beamline_name returns what is set in the environment variable BEAMLINE, or a default string.
The return of get_beamline_name is (often) used to create the BeamlinePrefix, which is used by both device_instantiation and device_factory to create the device prefix.

On e.g. i13-1-ws001, BEAMLINE=i13-1, and BeamlinePrefix("i13-1").beamline_prefix = "BL13I" however devices on i13-1 are actually prefixed BL13J.

Is using the environment variable to connect, other than in the cases of a simulated twin, a common behaviour that we need to support? This is done by the training_rigs, which share a dodal beamline module, and so must be distinguished.

Acceptance Criteria

• Specific criteria that will be used to judge if the issue is fixed

[noemifrisina]

IIRC, in a case such as i13-1, specifying the suffix in BeamlinePrefix should do the trick - even if it's not a very nice solution (and we might want something else in the long run):

from dodal.utils import BeamlinePrefix

bl = BeamlinePrefix("i13-1", suffix="J")

This should return bl.beamline_prefix = "BL13J"

Btw, just to make things more interesting, I'll note that the beamline prefix for both i19-1 and i19-2 is BL19I but that might be a single edge case.

[DominicOram]

FYI, this is a duplicate of #760. I will close the older one