Add automated test for "Make Version Summaries Mandatory"

The manual test is here: https://test.xwiki.org/xwiki/bin/view/Administration%20Tests/Make%20Version%20Summaries%20Mandatory

The test verifies that the Page Version Summaries mandatory feature from Administration is working properly.

Matrix discussion: https://matrix.to/#/!ikPtGZaGWtyblizzlR:matrix.xwiki.com/$16227980051996voTyG:matrix.xwiki.com?via=matrix.org&via=matrix.xwiki.com&via=dodsorf.as

Ilie Andriuta: Hi! Continuing the manual tests migration, there is a test about checking if the Page Version Summaries mandatory feature from Administration is working properly: https://test.xwiki.org/xwiki/bin/view/Administration%20Tests/Make%20Version%20Summaries%20Mandatory.

From what I've searched, I couldn't find automated tests for it. According to last time (see https://matrix.to/#/!ikPtGZaGWtyblizzlR:matrix.xwiki.com/$16215097374259jYrPc:matrix.xwiki.com?via=matrix.org&via=matrix.xwiki.com&via=dodsorf.as ) when the check was done for https://test.xwiki.org/xwiki/bin/view/Administration%20Tests/Change%20Default%20Editor was stated that most probably there are no automated tests for Edit Mode section.

I will create a JIRA task for it.