chore(e2e): Clean up enos variables (#6591)

* chore(e2e): No more required enos variables

# Conflicts:
#	.github/workflows/enos-run.yml

* CR

enos/modules/aws_boundary/variables.tf

@@ -337,7 +337,7 @@ variable "boundary_license" {
   description = "Boundary license (not needed for OSS, required for enterprise)"
   type        = string
   sensitive   = true
-  default     = null
+  default     = ""
 }
 
 variable "controller_config_file_path" {