Fix chronometer output if web interface is not installed

[ganto]

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• 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.
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What does this PR aim to accomplish?:
Fix wrongly shifted version list in chronometer output if AdminLTE web interface is not installed. Current output:

|¯¯¯(¯)_|¯|_  ___|¯|___        Core: v5.2.1.
| ¯_/¯|_| ' \/ _ \ / -_)        Web: v5.3.2.
|_| |_| |_||_\___/_\___|        FTL:
 ——————————————————————————————————————————————————————————

Note that the version of FTL is printed on the "Web" line.
Output of pihole version:

  Pi-hole version is v5.2.1 (Latest: v5.2.1)
  FTL version is v5.3.2 (Latest: v5.3.2)

How does this PR accomplish the above?:
Set Web version to "n.a." if not reported by pihole version:

|¯¯¯(¯)_|¯|_  ___|¯|___        Core: v5.2.1.
| ¯_/¯|_| ' \/ _ \ / -_)        Web: n.a.
|_| |_| |_||_\___/_\___|        FTL: v5.3.2.
 ——————————————————————————————————————————————————————————

What documentation changes (if any) are needed to support this PR?:
Not needed

[ganto]

Hmn, also the output of the debug script looks a bit weird. Will add another patch for that.

[ganto]

Hmn, also the output of the debug script looks a bit weird. Will add another patch for that.

It turned out the fix for the debug script might be a bit more controversy, so I decided to create a separate PR. See #3902.

This PR is then ready for review.

[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-v5-2-2-and-ftl-v5-3-3-released/41998/1