Fix url for the jail plugins upload

Merge:	releng/9.1.0
(cherry picked from commit 0d5d4b876ce93b74641b1a8e269e8081d1881170)
Fix delete of multiple plugins in the same jail

Merge:	releng/9.1.0
(cherry picked from commit 800ae58c5912de164e864fa6873301a8cb279239)
Add an arbitrary timeout to fetch plugins index

Merge:	releng/9.1.0
(cherry picked from commit 006d5e2b4b67d2027c6db89af14f2f1e5477e02f)