Enable scotch-metis and scotch-parmetis in cmake
Summary
Add default toolchain cmake flags to allow cmake to use metis and parmetis from scotch libraries.
Details
Since there is no METIS and ParMETIS library provided in the free repository of debian, the replacements scotchmetis and scotchparmetis are used. While these libraries are available in the image, they are ignored by cmake. It is necessary to enable them explicitly to allow tests to find the package METIS and ParMETIS with these replacements successfully. This MR adds the corresponding flags as toolchain cmake flags for debian-10, debian-11 and ubuntu-18.04, ubuntu-20.04 toolchains.