Since files containing system test output are no longer stored in test
subdirectories, bin/tests/system/clean.sh no longer needs to take care
of removing the test.output file for a given test as testsummary.sh
already takes care of that and even if a test suite terminates
abnormally and another one is started, tee invoked without the -a
command line switch overwrites the destination file if it exists, so
leftover test.output.* files from previous test suite runs are not a
concern. Remove the -r command line switch and the code associated with
it from the relevant scripts.
(cherry picked from commit b4d37878f6)
bc04dbf788