salt,tests: Allow to resolve registry endpoint from containers

[TeddyAndrieux]

In some cases, we may want to get some "stuff" from the internal registry
from inside a container (for example an operator that try to retrieve
some information from the registry).

Since we use a "fake" endpoint in containerd config file to reach the
registries, this commit make this "fake" endpoint also available when
resolving name with CoreDNS as we rewrite the "fake" endpoint name to
resolve to a non-headless service that points to the registry.

NOTE: We need to use a non-headless service as we want to forward the
port so that we have the same behavior as the fake endpoint configured
in containerd

[bert-e]

Hello teddyandrieux,

My role is to assist you with the merge of this
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[bert-e]

Waiting for approval

The following approvals are needed before I can proceed with the merge:

• the author

• one peer

Peer approvals must include at least 1 approval from the following list:

• @ChengYanJin

• @lucieleonard

• @JBWatenbergScality

• @alexandre-allard-scality

• @gdemonet

• @TeddyAndrieux

• @NicolasT

• @thomasdanan

[TeddyAndrieux]

/approve

[bert-e]

In the queue

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[bert-e]

I have successfully merged the changeset of this pull request
into targetted development branches:

• ✔️ development/123.0

The following branches have NOT changed:

• development/2.0
• development/2.1
• development/2.10
• development/2.11
• development/2.2
• development/2.3
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Please check the status of the associated issue None.

Goodbye teddyandrieux.