[misc] Added some Solr tests
- increased the test coverage limit
(cherry picked from commit 133ccfac1bd18e3802cdea3291608e81b67c054c)
[misc] minor test cleanup.
(cherry picked from commit c8c122cbf019bf2b69070c9a8819ecc3ad392862)
XWIKI-8816: List values are not correctly indexed in Solr in the objcontent field.
(cherry picked from commit eafad629108e7bf9eccf3151ee593dcbd1822f17)