test.py already support the routing of coverage data into a
predetermined folder under the `tmpdir` logs folder. This patch extends
on that and leverage the code coverage processing libraries to produce
test coverage lcov files and a coverage summary at the end of the run.
The reason for not generating the full report (which can be achieved
with a one liner through the `coverage_utils.py` cli) is that it is
assumed that unit testing is not necessarily the "last stop" in the
testing process and it might need to be joined with other coverage
information that is created at other testing stages (for example dtest).
The result of this patch is that when running test.py with one of the
coverage options (`--coverage` / `--mode-coverage`) it will perform
another step of processing and aggregating the profiling information
created.
Signed-off-by: Eliran Sinvani <eliransin@scylladb.com>
