WORKAROUND: Omit testing perl modules on install on SLC6 x64

For some reason a test case in `ExtUtil::MakeMaker-6.66` failed suddenly when installing the `ZeroMQ` perl modules. These are just test dependencies of the perl-services.
This patch disables the test runs when installing perl module. We do not want to be disturbed by failing test cases in perl dependencies during setup of our test machine.