Work around double parsing of ui_locales (#1469) #1507

Job	Run time
Test Demo Relying Party (18.x)	15s
Test Demo Relying Party (20.x)	14s
Test Package (Python 3.10, Django 4.2)	2m 30s
Test Package (Python 3.10, Django 5.0)	2m 47s
Test Package (Python 3.10, Django 5.1)	3m 18s
Test Package (Python 3.10, Django main)	3m 53s
Test Package (Python 3.11, Django 4.2)	2m 26s
Test Package (Python 3.11, Django 5.0)	2m 46s
Test Package (Python 3.11, Django 5.1)	3m 9s
Test Package (Python 3.11, Django main)	3m 49s
Test Package (Python 3.12, Django 4.2)	2m 26s
Test Package (Python 3.12, Django 5.0)	2m 49s
Test Package (Python 3.12, Django 5.1)	3m 19s
Test Package (Python 3.12, Django main)	3m 57s
Test Package (Python 3.8, Django 4.2)	2m 21s
Test Package (Python 3.9, Django 4.2)	2m 28s
Test successful	1s
	42m 28s

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