Revert "Temporarily suppress the age check for testing gerrit 2.4 upgrade."
Revert "Temporarily suppress the age check for testing gerrit 2.4 upgrade."

This reverts commit 5f680eee52c5a8aaacf0d7a5df16c043f75a499c.

No longer necessary, thus restore the check.

BUG=chromium-os:30306
TEST=manual

coreos/chromite,zhang0137/chromite,coreos/chromite,bpsinc-native/src_third_party_chromite,coreos/chromite,zhang0137/chromite,bpsinc-native/src_third_party_chromite,zhang0137/chromite,chadversary/chromiumos.chromite,chadversary/chromiumos.chromite,bpsinc-native/src_third_party_chromite