Bazel: Increase time limit for tests to 300 seconds

20 seconds (small size) doesn't seem to be enough on the CI: [1].

[1] https://gerrit-ci.gerritforge.com/job/Gerrit-verifier/1526/consoleText

Change-Id: I41dd945f425510c49603dafb3c2835a5ad9453d7
diff --git a/BUILD b/BUILD
index 1ca5610..364c45a 100644
--- a/BUILD
+++ b/BUILD
@@ -20,7 +20,7 @@
 
 junit_tests(
     name = "cookbook_tests",
-    size = "small",
+    size = "large",
     srcs = glob(["src/test/java/**/*IT.java"]),
     tags = [
         "cookbook-plugin",