Fix acceptance test heap size to 128m

Buck defaults to running 1.25 * ncpus tests in parallel.  If each test
uses a heap size of 128M then an 8 core system will need at least
1.25G of RAM for JVM heap during test execution.  The actual memory
used will of course be much higher due to JVM overhead.

Set a default memory for acceptance tests to prevent a huge explosion
during `buck test --all`.

Change-Id: I373df822c029d2dc24c625129f540211cda910e7
diff --git a/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/git/BUCK b/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/git/BUCK
index e6ac414..6014118 100644
--- a/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/git/BUCK
+++ b/gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/git/BUCK
@@ -3,13 +3,11 @@
 acceptance_tests(
   srcs = ['SubmitOnPushIT.java'],
   deps = [':util'],
-  vm_args = ['-Xmx512m'],
 )
 
 acceptance_tests(
   srcs = ['HttpPushForReviewIT.java', 'SshPushForReviewIT.java'],
   deps = [':push_for_review'],
-  vm_args = ['-Xmx512m'],
 )
 
 java_library(
diff --git a/gerrit-acceptance-tests/tests.defs b/gerrit-acceptance-tests/tests.defs
index 4bd40c1..f125a39 100644
--- a/gerrit-acceptance-tests/tests.defs
+++ b/gerrit-acceptance-tests/tests.defs
@@ -1,7 +1,7 @@
 def acceptance_tests(
     srcs,
     deps = [],
-    vm_args = []):
+    vm_args = ['-Xmx128m']):
   for j in srcs:
     java_test(
       name = j[:-len('.java')],