🌱 Reduce cyclomatic complexity of ReconcileLoadBalancer

[mdbooth]

This function had become genuinely too complex over time, to the point that even the linter was starting to complain about it when making almost any change.

This change refactors ReconcileLoadBalancer into several smaller logical functions which are much easier to read and reason about. It also revealed some trivial optimisations:

• Only fetch Octavia providers if we need them to create a new loadbalancer
• Only calculate allowed CIDRs once
• Don't re-fetch a loadbalancer to check it's active if it's already active

Apart from just the code cleanup, this has the benefit of not requiring these changes to be mixed into other PRs when the complexity exceeds the linter's threshold.

/hold

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: mdbooth

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[mdbooth]

/cc @MaysaMacedo as this touches some of your code.

[mdbooth]

I 100% agree about unit test coverage. However, this is basically just code motion so I can separate these changes from the other changes I'm making to the same code without triggering the gocyclo linter. IOW this is just yak shaving for me right now.

If you fancied taking the yak shears and writing some good unit tests while I get back to the API stuff I'd add to the beers I owe you.

[EmilienM]

/lgtm I'll let another reviewer take a look.

[mdbooth]

/hold cancel

[MaysaMacedo]

/hold

@mdbooth holding just to give a chance for you to check my comments, feel free to unhold once you checked them

[MaysaMacedo]

/lgtm

[EmilienM]

Restoring Maysa's LGTM, fixing unit tests and removing /hold. /lgtm /hold cancel