gitblit: remove nrpe from role

nrpe is now in base see https://gerrit.wikimedia.org/r/#/c/124576/ 
This means since the host already has nrpe via base there is no need to include it again

Change-Id: I923ef95ba531db1368a171035d6fe82138f7351e
Merge "gitblit: remove nrpe from role" into production