fix: prevent duplicate Host header in proxy configurations

[Annefr27]

In Ingress, when users define Host header in nginx.org/proxy-set-headers annotations, it was being duplicated because the code always added a default Host header automatically. The value set via the annotation had no effect.

Proposed changes

Remove the default "Host" header setting from nginx.ingress.tmpl and nginx-plus.ingress.tmpl template files.
Adds the "Host" header dynamically. If it is not defined in "master" or "minions", the default value "proxy_set_header Host $host;" is added.
This PR refers to Issue #8992

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• [ * ] I have read the CONTRIBUTING doc
• [ * ] I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• [ * ] I have rebased my branch onto main
• [ * ] I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

[github-actions]

✅ All required contributors have signed the F5 CLA for this PR. Thank you!
_{Posted by the CLA Assistant Lite bot.}

[Annefr27]

I have hereby read the F5 CLA and agree to its terms

[AlexFenlon]

Hi @Annefr27 thank you for making this,

I noticed the CLA has not been complete as the user @anne Peaudouyé has not accepted the CLA.

[Annefr27]

Hi @Annefr27 thank you for making this,

I noticed the CLA has not been complete as the user @anne Peaudouyé has not accepted the CLA.

Hi @AlexFenlon,

I don't understand why 2 contributors have been detected.
I'm the only contributor @Annefr27.
@anne Peaudouyé is a mistake, @anne has nothing to do with me.

[AlexFenlon]

Can you please rebase with just commit using the @Annefr27 user please as the checks we have will not work otherwise, sorry!