Drop -j option with no slice

This appears to confuse Numba's test suite in 0.59.0. Given it is a
no-op anyways, just drop it. Likely it was leftover when tweaking the
number of tests run before. The random selection of tests already used
should already be sufficient.

recipe/run_test.sh

@@ -52,7 +52,7 @@ python -m numba.tests.test_runtests
 
 if [[ "$archstr" == 'aarch64' ]] || [[ "$archstr" == "ppc64le" ]]; then
 	echo 'Running only a slice of tests'
-	$SEGVCATCH python -m numba.runtests -b -j --random='0.15' --exclude-tags='long_running' -m $TEST_NPROCS -- numba.tests
+	$SEGVCATCH python -m numba.runtests -b --random='0.15' --exclude-tags='long_running' -m $TEST_NPROCS -- numba.tests
 # Else run the whole test suite
 else
 	echo 'Running all the tests except long_running'