MXS-2900 Rename maxscale-system-test directory to system-test

A link with the old directory name is provided.

system-test/maxscale_process_user.cpp

@@ -0,0 +1,17 @@
+/**
+ * Check if Maxscale priocess is running as 'maxscale'
+ */
+
+#include "testconnections.h"
+
+int main(int argc, char* argv[])
+{
+    TestConnections test(argc, argv);
+
+    test.set_timeout(50);
+    auto res = test.maxscales->ssh_output("ps -U maxscale -C maxscale -o user --no-headers").second;
+    res = res.substr(0, strlen("maxscale"));
+    test.expect(res == "maxscale", "MaxScale running as '%s' instead of 'maxscale'", res.c_str());
+
+    return test.global_result;
+}