${cmake.testProgram} is replaced by an empty string

[cmorve-te]

As happened in #3280, I find that ${cmake.testProgram} is replaced by an empty string: https://github.com/microsoft/vscode-cmake-tools/blob/v1.19.52/src/ctest.ts#L1001

#3280 was fixed in #3631, but it would seem only for Google Test.
I'm using Catch2, with catch_discover_tests: https://github.com/catchorg/Catch2/blob/devel/docs/cmake-integration.md#automatic-test-registration

In #3631 there is this mention:

During testing with my projects, I discovered that the root cause of #3280 is how multi-root workspaces are handled.

I was not using a multi-root workspace, but I was using a workspace with two projects. Once I removed the workspace, and just opened the project with the tests directly, the problem has disappeared.