Remove local-ttl from set of default dnsmasq options

[DL6ER]

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• I have made only one major change in my proposed changes.
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• I have tested my proposed changes, and have included unit tests where possible.
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What does this PR aim to accomplish?:

Give users the ability to set local-ttl themselves if they want to.

How does this PR accomplish the above?:

We used local-ttl to control the TTL of blocked queries. We didn't want it to be too high to not render whitelisting ineffective. As pi-hole/FTL#1173 decouples the TTL of blocked queries from other local names, the reason to set this config option vanished.

What documentation changes (if any) are needed to support this PR?:

None