Bug 32824: Fix cataloguing/value_builder/unimarc_field_100.pl

Bug 32824: Fix cataloguing/value_builder/unimarc_field_100.pl

Use event parameter

This is part of the refactoring happening in bug 30975

Test plan:
1. Verify that the plugin continues to work as before

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
(cherry picked from commit 2d25c2860c4b06a63048834fb99b2968f1fd57b1)
Signed-off-by: Matt Blenkinsop <matt.blenkinsop@ptfs-europe.com>
(cherry picked from commit 8b19e1c6a72ed16f74b492796244360e0b6636ad)

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit ea894f3953ab5d9c35fbecaf9932fbae51ff346c)
Signed-off-by: Arthur Suzuki <arthur.suzuki@biblibre.com>