KVM: selftests: Re-enable access_tracking_perf_test

This selftest was accidentally removed by commit 6a581508
("selftest: KVM: Add intra host migration tests"). Add it back.

Fixes: 6a581508

 ("selftest: KVM: Add intra host migration tests")
Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20220120003826.2805036-1-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>