Fix DHCP tables button column

[yubiuser]

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What does this PR aim to accomplish?:

#1948 introduced text rendering to all table's column rendering. This fails in case of the DHCP tables, as the last column (Action) with the delete buttons should not be rendered as text.

https://github.com/pi-hole/AdminLTE/blob/21cba361e03bfbc6f241497066c2558a57c13c8e/scripts/pi-hole/js/settings.js#L245-L251

How does this PR accomplish the above?:

Limit the rendering to the first three columns

[DL6ER]

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/pi-hole-ftl-v5-12-web-v5-9-and-core-v5-7-released/51795/1