fix(operator): set ingester minimum available pods based on replication factor

[btaani]

What this PR does / why we need it:
Set the default value of the ingester's PodDisruptionBudget's minimum available pods to the replication factor

Which issue(s) this PR fixes:
Fixes LOG-6715

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Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
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1 out of 2 committers have signed the CLA.

✅ btaani
❌ Bayan Taani

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[JoaoBraveCoding]

I think we could move this function inside newIngesterPodDisruptionBudget.