PVC Pipe for sprinkler system broken in multiple places
I do not miss those California sprinkler systems.  

You have a long thin L shaped strip that needs to be watered, bounded by a wall on one side and concrete on the other.  

My proposition: abandon the underground sprinkler system.  It is loudly telling you it is more trouble and expense than it is worth.

Underground sprinklers are nice and unobtrusive for expanses of lawn and formal gardens.  You have neither.  You can easily run an aboveground length of PVC along the base of your wall.  You could salvage sprinkler units from your old system and position them along the new PVC completely above ground, pointing away from your wall.  

Everything will be in view and easy to maintain.  Leaks will be immediately obvious.  Your new pipe will be against the wall and so out of harm's way as regards people walking or mowing.  The roots can do what they want underneath.