Mock calls to rpm and dpkg from NetApp unit tests

This patch fixes an issue wherein several NetApp unit tests ran
OS rpm or dpkg commands because the callouts to these commands
were not mocked out during driver initialization.

It also replaces 'rpm -qa' with 'rpm -q' when that command is
invoked since the latter also works and is faster.

Closes-Bug: 1393545
Change-Id: I3d5cfeb2ee39ecb6af5b312dfa6c2a585cf8e0e3
(cherry picked from commit d555ca100aeb176bc021b8179d2a5cdfe10e168e)
Merge "Mock calls to rpm and dpkg from NetApp unit tests" into stable/juno