Print tail of logs in /var/log/lighttpd in debug run as well

[yubiuser]

By submitting this pull request, I confirm the following:

• I have read and understood the contributors guide, as well as this entire template.
• I have made only one major change in my proposed changes.
• I have commented my proposed changes within the code.
• I have tested my proposed changes, and have included unit tests where possible.
• I am willing to help maintain this change if there are issues with it later.
• I give this submission freely and claim no ownership.
• It is compatible with the EUPL 1.2 license
• I have squashed any insignificant commits. (git rebase)

Please make sure you Sign Off all commits. Pi-hole enforces the DCO.

---

What does this PR aim to accomplish?:
Print tail of logs in /var/log/lighttpd in debug run as well. Currently, only the first 25 lines are printed which might be not enough if a lot of errors occurred and older ones are different than newer ones.

How does this PR accomplish the above?:
Use head_tail_log function (which is also used for /var/log/pihole-FTL.log

[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-core-web-v5-2-and-ftl-v5-3-released/40909/1