Use DYNAMIC row format for server metadata tables that use mysql tablespace.

- If user specifies --innodb_default_row_format=redundant during
  database initialization, then the metadata tables fails to use key
  column which is larger than 255. This patch sets the row_format of
  metadata tables explicitly to DYNAMIC, which enables key column larger
  than 255.

- This keeps all the metadata tables in 'mysql' tablespace to use 'DYNAMIC'
  row format, keeping them uniform.

Change-Id: Icd0612e81bc700892253ef21cbd818097559422e