run doctor tests with different inspectors in sequence

As doctor tests have different inspectors, if they run in parallel
of one multijob, they will operator one cloud to create/delete
some resources, such as project, user, network and so on. It will
cause some conflicts.

Signed-off-by: dongwenjuan <dong.wenjuan@zte.com.cn>
Change-Id: I8111b28ad9de409542606f7be39a1ee0d838f8b6