feat: add logs for policy ignores

[davhdavh]

Description

Log when endpoints changes are dropped due to policy

Fixes #4815

Checklist

• Unit tests updated
• End user documentation updated

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[mloiseleur]

At first glance, it looks like it will generate (potentially) many logs for the same CLI switch.
Since this is the explicit purpose of this policy, I am not sure to see the value of this one.
Did I miss something ?

[davhdavh]

Don't think you missed anything. External-dns is already extremely spammy at debug level, and this certainly would not help with that.
There is however no current way to evaluate what the choosen policy actually does, and therefore there is great value in having it output what it actually does.