Handle the downstream_integration_test test arg (#973)

* Handle the `downstream_integration_test` test arg

* Fix Aqua test name

Author: jishnub

test/runtests.jl

@@ -6,11 +6,15 @@ using ParallelTestRunner
 # Start with autodiscovered tests
 testsuite = find_tests(pwd())
 
+if "--downstream_integration_test" in ARGS
+    delete!(testsuite, "AquaTest")
+end
+filtered_args = filter(!=("--downstream_integration_test"), ARGS)
+
 # Parse arguments
-args = parse_args(ARGS)
+args = parse_args(filtered_args)
 
 if filter_tests!(testsuite, args)
-    # Remove tests that shouldn't run on Windows
     delete!(testsuite, "testutils")
 end