Update the limit of length the history messages added by the workflow application to 1023 characters

The workflow application adds various history messages when pages transition from a state to another or when workflow operations take place.

Some of these messages have variable length, as they depend on messages inserted by the user (e.g. on the refusal of a publication).
Today, these messages are limited to 255 characters. The limit should be raised to 1023 characters now, as the limit was updated on the platform to 1023 as part of XWIKI-9327, for all XWiki versions above 5.2. Workflow uses 12.10 as minimum compatible version, so we can raise this limit safely.