CP-18860 move memory check to assert_valid_for_current_context
CP-18860 move memory check to assert_valid_for_current_context

The only place where the memory configuration is checked is
xapi_vm_memory_constraints.assert_valid_for_current_context.

Signed-off-by: Christian Lindig <4f88b50bc9dba63c9a7d9e208d4b3ac6f1a52800@citrix.com>

thomassa/xen-api,srowe/xen-api,thomassa/xen-api,Frezzle/xen-api,thomassa/xen-api,thomassa/xen-api,Frezzle/xen-api,srowe/xen-api,euanh/xen-api,srowe/xen-api,euanh/xen-api,srowe/xen-api,thomassa/xen-api,Frezzle/xen-api,euanh/xen-api,euanh/xen-api,thomassa/xen-api,Frezzle/xen-api,euanh/xen-api,Frezzle/xen-api,euanh/xen-api,srowe/xen-api