Get port number directly from pihole-FTL.conf

[rdwebdesign]

What does this PR aim to accomplish?

This PR simplifies the method used get the port used by FTL.

Please read the details on pi-hole/FTL#1445.

How does this PR accomplish the above?

• Remove the old code using FTL portfile
• code simplification

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

none

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