Revert "Add sequence support for externallinks table"

This reverts commit a33048bb8b4a1c7717c0760acd03563bf937687d.

Change-Id: I233eaf25c5e8b3ca41d828a47d57b050bd4796d3
(cherry picked from commit 695d6b92bff5e9c9e38ecbc0d91f3ec12d5eeb99)