Revert "[BEE-47337] added a delay of 3 seconds (#1122)" (#1151)

#1122 (comment)
notes that the sleep does not actually help the test other than to delay
its completion.

This reverts commit fb9d2ca.

src/test/java/org/jenkinsci/plugins/gitclient/GitAPITestUpdateCliGit.java

@@ -77,7 +77,7 @@ public void testSubmoduleUpdateWithThreads() throws Exception {
                 .execute();
         w.git.submoduleInit();
         w.git.submoduleUpdate().threads(3).execute();
-        Thread.sleep(3000);
+
         assertTrue("modules/firewall does not exist", w.exists("modules/firewall"));
         assertTrue("modules/ntp does not exist", w.exists("modules/ntp"));
         // JGit submodule implementation doesn't handle renamed submodules