Automatic merge from submit-queue (batch tested with PRs 46394, 46650, 46436, 46673, 46212)
refactor and export openstack service clients
**What this PR does / why we need it**:
Refactor and export openstack service client.
Exporting OpenStack client so other projects can use the them to call functions that are not implemented in openstack cloud providers yet.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
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