[BUGFIX] Fix questionable SQL schema definition for sys_file

Shorten field size for SHA1 (which is always 40 characters)
Remove index alias for sys_file.sha1

Resolves: #63434
Releases: master
Change-Id: Ia38d6308584594d320aa031ce7939fb3269fd52d
Reviewed-on: http://review.typo3.org/34785
Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Xavier Perseguers <xavier@typo3.org>
Tested-by: Xavier Perseguers <xavier@typo3.org>