MLECO-4490: Upgrade MLEK Catch Unit tests

*Removed default behaviour of unit-test executables to redirect output
to file.
*Accompanying change made to CI script to generate xml files there instead.
*Switched to newer minor version of Catch.
*Note: Support for simultaneous output to console and file is available in new major version (Catch 3).

Other unit test cleanup:
* Redundant warnings about common tests output removed
* Static cast added to silence compiler warning
* Removed additional printing in RNNoiseModelTests

Signed-off-by: Liam Barry <liam.barry@arm.com>
Change-Id: If9d7f366ec205a7cd49a45198a15867ef7b75afd