Log Backup in AlwaysOn In our current process, log backup is done by log shipping backup job.

Is there any need to configure backup job for transaction log in next AlwaysOn environment?

If we must configure backup, we want to set “checkpoint” with log backup job.
If you use Availability Groups you must do log backups. If you use Hallengren's backup solution then you'll need to set it up on both the primary and secondary node(s). Then direct the jobs it creates to point to the same network share. 

What will happen next is the script will create one directory for each server to hold system databases and any databases not within an availability group. Then another directory gets created with the availability group name and all the full and log backups go into there. 

That's important because your full backups and log backups might be split up between servers (so full backups happen on the primary and log backups happen on the secondary; there are settings so you can tweak this). So you want them all stored together in case you ever need to use them. 

AGs have a lot of things you have to know about. Monitoring so you know when they get out of sync, adding job steps for applications to make sure they only run on each server when it's primary (Hallengren's jobs have this built in), and patch order (don't failover with cluster manager ever). Don't put SSISDB into an AG without reading about it first. Don't use it wherever MSDTC is in use. 

You'll need to do some solid research but they're not that difficult. You'll learn edge cases as you go along.