Exclude IMBs from batch category picker

[confirmordeny]

See also:

https://www.whatdotheyknow.com/request/imb_reports_contacts_meeting_min/response/2542095/attach/2/2024.02.05%20FOI%20Ryan%20Jarvis%20IMB%20response.pdf

https://ico.org.uk/media/action-weve-taken/decision-notices/2023/4025101/ic-202747-g1r3.pdf

[HelenWDTK]

@confirmordeny Which tags? - hmp_imb, irc_imb, sthf_imb, yoi_imb, special_imb are the category ones, imb has some non-imbs on it at the moment, but might be better.

I think the tag/tags would just need adding here:

whatdotheyknow-theme/lib/model_patches.rb

Line 79 in e13affd

PublicBody.batch_excluded_tags += %w[school]