Improve CMake for Greentea tests #14851
Description
Description of defect
Before/while we add CTest support for Greentea tests, we might consider the following improvements in the existing definition to make things simpler to handle:
Target(s) affected by this defect ?
N/A
Toolchain(s) (name and version) displaying this defect ?
N/A
What version of Mbed-os are you using (tag or sha) ?
mbed-os-6.12.0
What version(s) of tools are you using. List all that apply (E.g. mbed-cli)
N/A
How is this defect reproduced ?
Check CMakeLists.txt for one of the tests.