didcot-tests: override file-in-unusual-dir and non-standard-dir-in-usr lintian tags

Signed-off-by: Dylan Aïssi <dylan.aissi@collabora.com>

debian/didcot-tests.lintian-overrides

 didcot-tests: no-manual-page
+# Tests files
+didcot-tests: file-in-unusual-dir
+didcot-tests: non-standard-dir-in-usr