validate: launcher: Remove log files for passing tests by default

Adding an option to keep them no matter what.
Log files are often pretty large and keeping them around can be annoying,
usually people won't look at logs files for passing tests, and we do not
even print them out.

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/9127>

subprojects/gst-devtools/validate/launcher/baseclasses.py

@@ -2321,6 +2321,12 @@ class _TestsLauncher(Loggable):
                         if test.max_retries:
                             test.max_retries -= 1
                             to_report = False
+                elif not self.options.keep_logs:
+                    for logfile in set([test.logfile]) | test.extra_logfiles:
+                        try:
+                            os.remove(logfile)
+                        except FileNotFoundError as e:
+                            self.error(f"{logfile} doesn't exist {e}, can't remove")
                 self.print_result(current_test_num - 1, test,
                     retry_on_failures=retry_on_failures,
                     total_num_tests=total_num_tests)