[misc] Fix URI encoding (left over from XWIKI-9025).

(cherry picked from commit e09bf886eaf2a4258f85d25d593b51f3cd3a20a3)

Conflicts:
	xwiki-platform-core/xwiki-platform-rest/xwiki-platform-rest-server/src/main/java/org/xwiki/rest/internal/resources/BaseAttachmentsResource.java