Remove UK overlays for Middlesex and Wiltshire

[manewitz]

This came up because we use carmen to populate a "subregion" dropdown that is loaded after a user selects a country. We had several people write in about the UK list not being accurate.

Middlesex is a "Historic County" and not ISO-recognized as a subregion. Wiltshire is a "Unitary Authority" and already in the base library. Even if their classifications had been corrent, the overlays removed had placed them at the wrong level in the region/subregion yaml hierarchy.

Before:

> uk = Carmen::Country.named('United Kingdom')
> uk.subregions.map(&:name).sort
=> [
    [0] "England",
    [1] "England and Wales",
    [2] "Great Britain",
    [3] "Middlesex",
    [4] "Northern Ireland",
    [5] "Scotland",
    [6] "United Kingdom",
    [7] "Wales; Cymru",
    [8] "Wiltshire"
]

After:

> uk.subregions.map(&:name).sort
=> [
     [0] "England",
     [1] "England and Wales",
     [2] "Great Britain",
     [3] "Northern Ireland",
     [4] "Scotland",
     [5] "United Kingdom",
     [6] "Wales; Cymru",
   ]

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Before submitting the PR please make sure that you have done the following:

• I have read the Wiki on how to make geographic changes if this PR modifies geographic data
• I have added a CHANGELOG entry if appropriate

[manewitz]

@swcraig let me know how this looks when you have some bandwidth

[swcraig]

Thanks for the PR! I will take a closer look tomorrow.

[swcraig]

Thanks for the contribution @manewitz. This looks great. I added a commit to resolve a merge conflict with the CHANGELOG I created by merging #267.

[manewitz]

(airhorn intensifies) Thank you!

[manewitz]

@swcraig any reason you are holding on pushing out the new version?

[swcraig]

@manewitz No particular reason, the new version is out now. I'll work on a more consistent release schedule going forward. Thanks again for the contribution.