Make error message for rejecting Egit placeholder Change-Id consistent

In the commit dialog Egit uses a placeholder for the Change-Id
("I0000000000000000000000000000000000000000") which it replaces later
with the real Change-Id. Some users thought that this placeholder also
works on the commandline, but of course there the replacement wasn't
done. As result of this there were lots of changes with this
placeholder Change-Id (as from the format it's a valid Change-Id) and
users got confused about updating each other changes. To prevent this
Gerrit rejects this placeholder Change-Id as invalid. However the
message for this was inconsistent with the message that is used for
other invalid Change-Ids.

Also all validations should be done in CommitValidators, but the check
for the Egit placeholder Change-Id was still done in ReceiveCommits.
Move the check to the right place.

Change-Id: I11c3c1a2d0023c4852d2fa6ec3a54a1245030377
Signed-off-by: Edwin Kempin <ekempin@google.com>

gerrit-acceptance-tests/src/test/java/com/google/gerrit/acceptance/git/AbstractPushForReview.java

@@ -708,12 +708,14 @@ public abstract class AbstractPushForReview extends AbstractDaemonTest {
     createCommit(testRepo, "Message with invalid Change-Id\n"
         + "\n"
         + "Change-Id: I0000000000000000000000000000000000000000\n");
-    pushForReviewRejected(testRepo, "invalid Change-Id");
+    pushForReviewRejected(testRepo,
+        "invalid Change-Id line format in commit message footer");
 
     ProjectConfig config = projectCache.checkedGet(project).getConfig();
     config.getProject().setRequireChangeID(InheritableBoolean.FALSE);
     saveProjectConfig(project, config);
-    pushForReviewRejected(testRepo, "invalid Change-Id");
+    pushForReviewRejected(testRepo,
+        "invalid Change-Id line format in commit message footer");
   }
 
   private static RevCommit createCommit(TestRepository<?> testRepo,