Improve loop for getAllQueries from FTL's memory

[yubiuser]

• 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.
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What does this PR aim to accomplish?:
This PR reduces the memory needed by api.php?getAllQueries to process every requested record.
It's basically a copy of #2114 but for the current in-memory data served by FTL.

Usually we have seen the out-of-memory error when requesting large amounts of data from the long-term database, but currently there is an issue on discourse where the in-memory data is also too huge to process getAllQueries

https://discourse.pi-hole.net/t/all-queries-are-not-working/54711

How does this PR accomplish the above?:
The old code used to generate and return the request adds all records into a single array. This array grows for each record (and there are many many records).
Only at the end (and if memory holds up), it transforms the entire array into JSON and sends all at once as a string.

The new code outputs each record as a string immediately.
This way, there is no array and the memory for each iteration is always the same.
The web server is responsible for sending the "text stream", nothing else needs to change.

[yubiuser]

Has been confirmed working in the linked discourse topic.

[DL6ER]

There are merge conflicts.

I think it's worth noting that this removed a feature of the API that allows combining multiple requests in the same API call. I don't really know if it is every used for this endpoint, but we use it elsewhere. Example: Requests like api.php?summary&getAllQueries change behavior in this PR (summary is now ignored)

[yubiuser]

Merge conflicts resolved.

DL6ER made a good point. I searched for api.php? within the source and could not find any occurrence with getAllQueries and something else. But user scripts might use it. Not sure how to proceed. Is this a show stopper?
_

My last commit (moving the exit) made me think if the exit in this PR is also at the wrong spot? @rdwebdesign

[rdwebdesign]

Looks fine.

[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-v5-15-web-v5-12-and-core-v5-10-released/54987/1

[pralor-bot]

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

https://discourse.pi-hole.net/t/confusion-from-the-main-display-screen/56102/4