default or selected kernelversion does not have config value CONFIG_ION_TEST.
Result is shown for kernelversion 6.5.1

Ion Test Device

modulename: ion_test.ko

configname: CONFIG_ION_TEST

Linux Kernel Configuration
└─>Device Drivers
└─>Staging drivers
└─>Android
└─>Ion Memory Manager
└─>Ion Test Device
In linux kernel since version 3.14 (release Date: 2014-03-30)  
Choose this option to create a device that can be used to test the
kernel and device side ION functions.

source code: