fix(VSnackbar): fix class name for center location #19102

# to view logs

Job	Run time
pre_job	4s
Build vuetify	1m 53s
Test (Cypress)	9m 38s
Test (Jest)	1m 21s
Lint (--scope vuetify --scope @vuetify/api-generator)	1m 8s
Lint (--scope vuetifyjs.com)	3m 38s
Build docs	0s
publish-docs	0s
deploy	0s
	17m 42s

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