LIMS-2139: Dont display special beam as beam dumps

[ndg63276]

JIRA ticket: LIMS-2139

Summary:

If the Synchrotron is in "Special Beam" mode, the visit stats page shouldn't record that as a beam dump, as it is usable beam. See eg https://ispyb.diamond.ac.uk/stats/visit/mx41044-27

Changes:

• Move the name of the beam mode PV into config
• Also put the "beam on" PV values into the config
• Remove arbitrary 3600 seconds offset removed in one file and re-added in another
• Use the start of the beam dump or the start of the visit, whichever is later, as users should not care about the time before their visit
• Tidy some of the loop logic to make the workings clearer
• Fix bug where beamlines without a defined elog logbook would throw an error

To test:

• Add these to the config

    $beam_mode_pv = 'CS-CS-MSTAT-01:MODE';
    $beam_mode_pv_beam_on_values = array(4, 5);

• Go to the visit stats for a page with lots of special beam time, eg /stats/visit/mx41044-27. Check there are no beam dumps shown in the visit breakdown or the pie chart
• Go to the visit stats page of a visit that has a beam dump, eg /stats/visit/in37773-44. Check the beam dump lasts 2.3 hours
• Go to the visit stats page for a visit that started during a beam dump, eg /stats/visit/mx41137-28. Check the beam dump starts when the visit starts at 14:56, finishes at 09:00, and the beam dump duration is therefore 18.1 hours.
• Go to the visit stats page for a visit that ended during a beam dump, eg /stats/visit/mx40148-41. Check the beam dump starts correctly at 9am March 13th, and runs until the vist ends at 14:43 March 14th, and thus displays as 29.7hrs (32 hours total)
• Go to the visit stats page for a visit during BST, eg /stats/visit/mx40148-20. Check the beam dump starts from 9am.
• Go to the visit stats page for an i02-1 visit eg /stats/visit/mx41137-28. Check no errors occur from the fact that i02-1 has no logbook defined in $bl_types