fixed tests

6 jobs for 23-define-estimator-interface in 10 minutes and 27 seconds (queued for 1 second)
Name Stage Failure
failed
mpitest-mlmc Test
[----------] 2 tests from TestWelfordAggregate1e6Samples (14 ms total)

[----------] Global test environment tear-down
[==========] 7 tests from 3 test suites ran. (31 ms total)
[ PASSED ] 7 tests.
end program after 0.14 seconds on 4 procs at Wed May 12 14:12:10 2021
6/6 Test 6: TestWelfordAggregateMPI ...................... Passed 0.52 sec
Cleaning up file based variables
ERROR: Job failed: exit code 1