[BUGFIX] Remove duplicate database indices

Percona toolkit found some duplicate
indices in some ext_tables.sql.
Remove or update the mentioned indices.

Resolves: #82671
Releases: master,8.7
Change-Id: Icdb60e2ee9f16cad097c0371e258e2c176c3b50c
Reviewed-on: https://review.typo3.org/56856


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Tested-by: Mathias Schreiber <mathias.schreiber@typo3.com>
Reviewed-by: Alessandro <alessandro.filira@pallino.it>
Tested-by: Alessandro <alessandro.filira@pallino.it>
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>