Description:
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This WL will remove YEAR(2) cloumn. It supports:
F1: Remove some old codes about YEAR(2).
F2: Must not create YEAR(x!=4) column.
    Only support YEAR/YEAR(4) column.
F3: Must not ALTER TABLE a column to YEAR(x!=4) column.
F4: Run DML statements on existent legacy YEAR(X!=4) column will be given a
    error.
F5: Run SHOW CREATE TABLE statement on existent legacy YEAR(X!=4) column will
    be given a warning.
F6: Must not replicate CREATE YEAR(x!=4) column from 5.5 or 5.1 to this WL.