Base expert icon on expert class not FTL advanced flag

[yubiuser]

What does this PR aim to accomplish?:

Show the wrench icon for expert level settings based on the expert class of the the parents (set manually) not based on the FTL 'advanced-setting' flag.

This PR is the counterpart for pi-hole/FTL#1883 which will remove the advanced flag, but keeps the wrench icon at the setting boxes when they are considered expert-level.

For background see #2882 (comment)

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[PromoFaux]

Tested and working as expected. e.g Running this branch alongside the companion FTL PR, the wrench icon is restored on the "Query Anonymization" box where it is not present with the tweak/remove_expert_flag FTL branch alone.

@yubiuser DCObot is not happy it seems.... Once that's sorted I'll drop an approve!

[yubiuser]

I don't know why it's not happy. The commit is signed-off...