Fix EZP-22487: paragraph drops its class when alignment is applied in ezoe

JIRA: https://jira.ez.no/browse/EZP-22487

# Description

See this screencast: https://mugo.viewscreencasts.com/1b9932098b8c4b0fb5c7bf8cf77aa0a2 Basically, if an element has both a custom class and one of the `ezoeAlign*` class, the PHP parser will drop the complete class attribute. This patch makes sure the `ezoeAlign*` classes are removed before being handled server side.

# Tests

manual test