chore(source): code coverage and refactoring of traefik

[ivankatliarchuk]

Description

Quite often we have Traefik as ingress. I think is worth to improve code coverage and slightly refactoring. Mainly

• Reduce code duplication, as functions are very similar. Example; The methods ingressRouteEndpoints, ingressRouteTCPEndpoints, ingressRouteUDPEndpoints, oldIngressRouteEndpoints, oldIngressRouteTCPEndpoints, and oldIngressRouteUDPEndpoints share a lot of similar logic.
• Consistent string trimming: Use strings.Trim(host, "")` in all functions for consistency.
• Comment clarity
• Combine Filtering Functions; The filtering functions filterIngressRouteByAnnotation, filterIngressRouteTcpByAnnotations, and filterIngressRouteUdpByAnnotations are nearly identical.
• Added unit tests, to improve code coverage. Still below 80%, current is 65%

I've no idea why the code is copied https://github.com/kubernetes-sigs/external-dns/blob/master/source/traefik_proxy.go#L764-L1094. At some point, we better rely on official code from here https://github.com/kubernetes-sigs/external-dns/blob/master/source/traefik_proxy.go#L764-L1094 as example. Less code -> less to bugs

Checklist

• Unit tests updated
• End user documentation updated

[mloiseleur]

@linoleparquet Do you think you can review this PR ?

[linolayani]

lgtm 👍

[k8s-ci-robot]

@linoleparquet: changing LGTM is restricted to collaborators

In response to this:

lgtm 👍

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[ivankatliarchuk]

If possible can we first approve/merge the other pr #5304, mainly due to it's size

[mloiseleur]

@ivankatliarchuk Once you have rebased this PR, I think we can merge it, too.

[ivankatliarchuk]

/label tide/merge-method-squash

[ivankatliarchuk]

rebased

[mloiseleur]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: linoleparquet, mloiseleur

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