Add automated test for "Live macro rendering when editing in place"

The manual test is here: Live macro rendering when editing in place

Existing automated coverage

• InplaceEditIT#macroPlaceholder: In-place edit: inserts the Id macro (parameter set in the macro modal, Submit) and the Children macro via quick actions; asserts the Children macro output is rendered right after insertion.
• MacroIT#children: Children macro output rendered in the standalone editor.

Missing automated coverage

• Edit a page in-place, open Insert > Other Macros, select a macro with visible output (e.g. Documents/Pages), fill its options, Submit.
• Assert the macro output is rendered in the editing area immediately after Submit (no placeholder).

Suggested location: xwiki-platform-core/xwiki-platform-edit/xwiki-platform-edit-test/xwiki-platform-edit-test-docker/src/test/it/org/xwiki/edit/test/ui/InplaceEditIT.java

Found by comparing the XWiki 18.4.4 manual test runs against the automated tests on master (a0055f10a1a).