chore(aws): document and test behavior for ALB and NLB

[ivankatliarchuk]

What does it do ?

I've added only tests, to explicitly capture behaviour and make it obvious. At the memont, to my understanding AWS ALB controller for NLB creates two hostnames, one prefixed with internal-.

I've explained solution here #5661 (comment).

If we think there are other options, like flag, annotation or some sort of regex or filter I could implement in this or follow-up PR.

It's great to have a better support for AWS ALB, like automated management of records, same time the ALB controller behaviour is quite unpredictable and not well documented. Happy to follow advice

Motivation

Fixes #5661

More

• Yes, this PR title follows Conventional Commits
• Yes, I added unit tests
• Yes, I updated end user documentation accordingly

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[coveralls]

Pull Request Test Coverage Report for Build 20618885687

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
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• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 384 unchanged lines in 23 files lost coverage.
• Overall coverage decreased (-0.06%) to 78.861%

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Files with Coverage Reduction	New Missed Lines	%
gateway_udproute.go	2	92.59%
gateway_grpcroute.go	2	92.59%
gateway_tlsroute.go	2	92.59%
gateway_httproute.go	2	92.59%
gateway_tcproute.go	2	92.59%
source.go	2	72.22%
openshift_route.go	3	85.0%
gateway_hostname.go	4	42.86%
contour_httpproxy.go	7	84.35%
skipper_routegroup.go	7	39.34%

Totals
Change from base Build 20569555245:	-0.06%
Covered Lines:	15814
Relevant Lines:	20053

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💛 - Coveralls