Automatic merge from submit-queue
OpenStack LBaaSV2: EnsureLoadBalancer now updates instead of recreates existing LBs
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**What this PR does / why we need it**: Current LBaaSV2 integration recreates existing LBs and causes service downtime and floating ip rotation. New implementation updates LBs without service downtime or any ip rotation.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes#32794
**Special notes for your reviewer**: I really need this before we can move to production with kubernetes. Getting this to v1.4 would be really great. I have performed plenty of testing; lb and listener creation, port changing and listener update, multiple listeners for multi-port LBs, and deletion. Seems to work flawlessly.
**Release note**:
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