Bug 32819: Fix cataloguing/value_builder/stocknumberam123.pl

Bug 32819: Fix cataloguing/value_builder/stocknumberam123.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 cc59823fa3cc25f79a4b247d6c66a07dfedbf045)
Signed-off-by: Jacob O'Mara <jacob.omara@ptfs-europe.com>
(cherry picked from commit a06f4336dcf4b9809f18f588839ac33c9901759e)
Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>
(cherry picked from commit 96bda428387d1ece43ee8a52cd06309b4054fd9a)
Signed-off-by: Arthur Suzuki <arthur.suzuki@biblibre.com>