I have written 3 functions as follows
In [3] function, I will call [2] function to get users using Azure function url as below:-
https://hdidownload.azurewebsites.net/api/getusers
Is there any other way to call Azure function with in another Azure function without full path as above?
There's nothing built-in in Function Apps to call one HTTP function from other functions without actually making the HTTP call.
For simple use cases I would just stick to calling by full URL.
For more advanced workflows, have a look at Durable Functions, paticularly Function Chaining.