What happened to the Crickets Ringtone?

It's still there. Based on what I see in your screenshot, you're looking at the Classic Alert tones. Make sure you're looking in Ringtones>Classic. Be careful you don't scroll past it and go to the "Classic" at the bottom of the page. That's classic alert tones.

Go to Settings > Sounds & Haptics > Ringtone > Classic > Crickets

It is most likely no longer available. You can submit your feedback using the link below or purchase it through the iTunes store.

https://www.apple.com/feedback/

Glad you found it!