enable optional subPath for logs volume mount

[gbloisi-openaire]

Users may want to have their logs on a volume that includes other things and as such want to use a subPath on the Volume Mount. This is similar to how the gitSync and dags Volume Mounts are setup (see PR 22323 )

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[boring-cyborg]

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[gbloisi-openaire]

Anyone could check?
Even though many lines have been added the change is relatively simple as it replicates the pattern for subPath support in other volumes. It has been tested in a deployment where logging goes to a shared nfs volume.

[potiuk]

Can you add a helm-test for that one?

[gbloisi-openaire]

@potiuk I just added tests using as model the ones written for #22323 keeping in consideration that now there is a different rending depending on airflow version.

[potiuk]

Let's see if CI agrees

[boring-cyborg]

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