[BUGFIX] Add missing SQL index for EM repository update

Due to the large number of extensions, the query that
checks if an extension exists needs an index that
covers all of the columns used for joining/clauses.

Change-Id: I73bd78a7d923a1e49594374b0dd8fee270fa30a3
Releases: 8.7, master
Resolves: #81097
Reviewed-on: https://review.typo3.org/52670


Tested-by: TYPO3com <no-reply@typo3.com>
Reviewed-by: Christer V <cvi@systime.dk>
Reviewed-by: Andreas Fernandez <typo3@scripting-base.de>
Tested-by: Andreas Fernandez <typo3@scripting-base.de>
Reviewed-by: Michael Oehlhof <typo3@oehlhof.de>
Reviewed-by: Oliver Klee <typo3-coding@oliverklee.de>
Reviewed-by: Jan Helke <typo3@helke.de>
Tested-by: Jan Helke <typo3@helke.de>