Reorganised prepare scripts for tests

[oleg68]

This PR

• moves installing cpptrace to a separate script prepare-cpptrace.bash
• removes the special script prepare-debian-for-tests.sh
• added the steps necessary for tests to the normal installation scripts prepare-debian-based.sh and prepare-fedora.sh

[larspalo]

I'm not fond of adding this downloading and building of a third party software as a requirement as the tests are (and should always be) optional.

[rousseldenis]

I'm not fond of adding this downloading and building of a third party software as a requirement as the tests are (and should always be) optional.

Yes, at least that should be optional when wanting to run tests. That was the philosophy before this.

[oleg68]

@larspalo @rousseldenis Now by the testing software is not installed unless the tests parameter is passed