Fix Verilator detection by tests

Created by: valentinThomazic

Related to : https://github.com/openhwgroup/cva6/issues/1795.

• The detection of the tools should now work as expected.
• Also moved the setup-env.sh execution in the smoke-tests since it is intended to be ran when tools are installed.
• Added a failsafe in install-verilator.sh in case several verilator directories are installed in the tools directory (the first one returned by grep is picked).
• Use setup-env.sh instead of install-cva6.sh and install-riscv-dv.sh in linux.sh test since they no longer exist in the repo