tests: Use insecure random for acceptance tests

This reduces startup time for JUnit tests which need random data
to seed the SSHD PRNG. Using /dev/./urandom is necessary as a
workaround on modern Java versions[1].

[1] https://bugs.openjdk.java.net/browse/JDK-6202721
Change-Id: I944f73e93dca131c6947779a3f9f4fb8d87b9a54

gerrit-acceptance-tests/tests.defs

@@ -10,9 +10,12 @@ def acceptance_tests(
     labels = [],
     source_under_test = [],
     vm_args = ['-Xmx256m']):
-  from os import environ
+  from os import environ, path
   if not environ.get('NO_BOUNCYCASTLE'):
     deps = BOUNCYCASTLE + deps
+  if path.exists('/dev/urandom'):
+    vm_args = vm_args + ['-Djava.security.egd=file:/dev/./urandom']
+
   for j in srcs:
     java_test(
       name = j[:-len('.java')],