ProtoGen: Don't include version in output

Google is the only user of this, and we no longer need this file to
change every time we import Gerrit.

Change-Id: I19e5238f236ec47c9893b74780cfe9768a1b5d78

resources/com/google/gerrit/pgm/ProtoGenHeader.txt

@@ -11,8 +11,6 @@
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
-//
-// Gerrit Code Review (version @@VERSION@@)
 
 syntax = "proto2";