[CMake] CMP0026 - Disallow use of the LOCATION target property

[Jifeng ZHANG]

Thank you Steve and NoRulez.

We actually make some manipulations on the string (TEST_PATH) that
returned from get_target_property, before we pass it to add_test.

So if we directly pass the generator expression, it won't work. We
need to change this part obviously.

Any idea when CMake 4.0 is planned to release? So we can get a general
idea when the old behavior will stop working.

Regards,

Jifeng