fix "873868: NetApp: move split job to end"

[chuan137]

The patch "NetApp: move split job to end" (https://review.opendev.org/c/openstack/manila/+/873868) was developed for fixing the issue "NetApp volume busy on create from snapshot Edit" (https://bugs.launchpad.net/manila/+bug/2007970)

However, it does not work as expected. To reproduce the issue, create a share from a snapshot and check the execution steps on the backend. For example, from NetApp's audit log,

> "Fri Jul 21 11:26:25 2023" stnpa1-02-st051 volume-clone-create Success -
> "Fri Jul 21 11:26:25 2023" stnpa1-02-st051 volume-clone-split-start Success -
> "Fri Jul 21 11:26:25 2023" stnpa1-02-st051 volume-modify-iter Success -

The clone split is started before modifying the volume attributes. As a result, the issue in #2007970 can still happen, namely modifying volume attributes fails because of "Volume busy".

Looks like that the fix in https://review.opendev.org/c/openstack/manila/+/873868/1/manila/share/drivers/netapp/dataontap/cluster_mode/lib_base.py#b1567 overlooked that the split variable can be overridden by the "split" field in provisioning_options.

Best,
Chuan