SharedLock: fix a wrong unit-test helper code
SharedLock: fix a wrong unit-test helper code

The _doItDelete helper code was supposed to be used to dispatch threads that
deleted the SharedLock. It actually just acquired it exclusively. This remained
unnoticed as the helper thread is just used to test interaction, not the delete
code by itself, and delete requires an exclusive acquire anyway.

Reviewed-by: imsnah


yiannist/ganeti,ganeti/ganeti,mbakke/ganeti,andir/ganeti,apyrgio/ganeti,andir/ganeti,onponomarev/ganeti,grnet/snf-ganeti,ganeti-github-testing/ganeti-test-1,andir/ganeti,mbakke/ganeti,yiannist/ganeti,ganeti/ganeti,ganeti-github-testing/ganeti-test-1,bitemyapp/ganeti,dimara/ganeti,apyrgio/snf-ganeti,apyrgio/ganeti,grnet/snf-ganeti,apyrgio/snf-ganeti,yiannist/ganeti,dimara/ganeti,ganeti/ganeti,leshchevds/ganeti,bitemyapp/ganeti,leshchevds/ganeti,mbakke/ganeti,leshchevds/ganeti,onponomarev/ganeti