tests: don't log filename nor color in unit tests

In experr, we had line numbers in log output, which might change. Also, for
make distcheck, the path of the source file might have some '../../' added in
the log output (to indicate the src dir as seen from the build dir).

Fix both by dropping source file and line.

Also drop color while at it.

Change-Id: Ie76384c4176ce0a7d89d093f2efb848fe3f19400
2 files changed