Make Code-Review label values' meaning clear to non-maintainers

Currently the labels look like a direct suggestion to a maintainer
dealing with the change, but even being interpreted this way, -1 label
sounds strange as "didn't submit" doesn't match the fact nobody has
submitted anything yet.

What's worse, new contributors have every right to assume that the
message is addressing them, and upon receiving an email saying "I
would prefer you didn't submit this" they mistakenly think that the
word "submit" refers to their action of posting for review, there's
nothing to indicate this part is directed to the maintainer. Also,
most people have never seen the "Submit" button, that's a process
detail known to the maintainers but not the general public.

This is confirmed by real-life observations of contributors to the
OpenOCD project, I know at least three persons who got somewhat
offended by receiving such a message from the review system.

Change-Id: I035a615a6caf6e085edd5827f3bfe33342156324
Signed-off-by: Paul Fertser <fercerpav@gmail.com>

gerrit-server/src/main/java/com/google/gerrit/server/schema/AllProjectsCreator.java

@@ -213,8 +213,8 @@ public class AllProjectsCreator {
         new LabelValue((short) 2, "Looks good to me, approved"),
         new LabelValue((short) 1, "Looks good to me, but someone else must approve"),
         new LabelValue((short) 0, "No score"),
-        new LabelValue((short) -1, "I would prefer that you didn't submit this"),
-        new LabelValue((short) -2, "Do not submit")));
+        new LabelValue((short) -1, "I would prefer this is not merged as is"),
+        new LabelValue((short) -2, "This shall not be merged")));
     type.setAbbreviation("CR");
     type.setCopyMinScore(true);
     c.getLabelSections().put(type.getName(), type);