Optimised taglocations API

[17sushmita]

Fixes #9946

Very similar fix as in #9940
We can further optimise it but this fix also optimises very significantly.

• PR is descriptively titled 📑 and links the original issue above 🔗
• tests pass -- look for a green checkbox ✔️ a few minutes after opening your PR -- or run tests locally with rake test
• code is in uniquely-named feature branch and has no merge conflicts 📁
• screenshots/GIFs are attached 📎 in case of UI updation
• ask @publiclab/reviewers for help, in a comment below

Before:

GET: http://publiclab.org/api/srch/taglocations?nwlat=52&selat=-52&nwlng=-150&selng=150
Time: 19.43s

After:

GET: http://publiclab.org/api/srch/taglocations?nwlat=52&selat=-52&nwlng=-150&selng=150
Time: 1991ms

[gitpod-io]

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[17sushmita]

Also noting that we are currently extracting all the node ids and then selecting only those node ids using the IN operator in SQL which I think can be optimised by skipping the redundant steps and merging both in the same query. However, I'm not very sure, it will require a bit of research.

[17sushmita]

Also we can think of implementing caching as suggested by @jywarren by removing the precision and storing cache for rounded off values.

[jywarren]

Hooray!!!! Excellent work!!!

[jywarren]

🎉 🎉 🎉 🎉 🎉

[jywarren]

Hi @17sushmita did some of what I'm talking about in #9946 (comment) make sense to you? Did you want to dive deeper into it with Barun and I?