tool: Read name prefix from /etc/wmcs-project
tool: Read name prefix from /etc/wmcs-project

Hardcoding "tools." does not work on toolsbeta. Instead use an approach
similar to what's in webservice and read the prefix from
/etc/wmcs-project directly.

Bug: T290325
Change-Id: Iefacf97ed2474d21d8bd138654d8afea5708d93c

wikimedia/operations-software-tools-manifest