Use no_timer_check with soft-qemu

The Linux kernel timer check not working properly
when the hypervisor's thread preempted by the host CPU scheduler.

The timer check is automatically disabled with other types
of hypervisors including the hardware accelerated kvm,
but timer_check is not disabled when qemu used without hardware acceleration.

This issue is frequently mischaracterized as an SSH connectivity issue and
causes rechecks and occasional boot failures.

This change adds no_timer_check kernel parameter when we are using
uec images with qemu.

Closes-Bug: #1312199
Change-Id: I3cfdfe9048fe219fc12cdac8a399b496f237e55e
Fix infinitely reschedule instance due to miss retry info

The logic of building instance is moved from scheduler to conductor,
But 'retry' info is still populated at scheduler manager, and that
can't be take back from rpc call. This patch moves the retry checking
logic into conductor, and keep the old 'schedule_run_instance'
same as before.

Change-Id: I4efafe815e8623881e6c037eb9d04c0dbb7052a2
Partial-Bug: #1326207
Remove unused code from test_compute_cells

The decorator was introduced in change
I048cc532614c602f3aa6b539fb51e951174e4598 - but it's usage has since
been removed.

Change-Id: Icf00f85a72198aeaf1ac7d32fb492b020399e3b4
Merge "Use no_timer_check with soft-qemu"
Merge "Remove unused code from test_compute_cells"
Merge "Fix infinitely reschedule instance due to miss retry info"