Prepare for enabling H302 rule (api/compute/admin)

We can use H302 rule but ignore it now. This commit prepares for
enabling H302 rule. But this commit modifies a part of Tempest only
because if we fix all of them at one time, it's hard to merge this
commit.

    ---------------
    tempest/api/compute/admin     <- This patch
    tempest/api/compute/{c*,f*,i*,s*,t*}
    tempest/api/compute/{v3,volumes},data_processing
    tempest/api/identity/admin
    tempest/api/image
    tempest/api/{n*,o*,t*}
    tempest/api/volume,tempest/*
    tempest/services/compute/json
    tempest/services/compute/v3/json
    tempest/services/compute/xml
    tempest/services/identity
    tempest/services/{im*,n*,o*,t*}
    tempest/services/volume
    tempest/clients.py: TBD
    ---------------

Change-Id: Id993c8b157c0b1256aa17c2b8e8f8da46111c521
Merge "Prepare for enabling H302 rule (api/compute/admin)"