DDC-4001: [GH-1558] [RFC] remove indexes overruled by primary key

[doctrinebot]

Jira issue originally created by user @doctrinebot:

This issue is created automatically through a Github pull request on behalf of guilhermeblanco:

Url: #1558

Message:

There can be unique indexes automatically created for join column.
If join column is also primary key we should keep only primary key on this column.

Oracle does not allow having both unique index and primary key on the same column, it is useless for mysql too.
(Previously it was done by DBAL, but now it allows duplicate indexes)

[doctrinebot]

Issue was closed with resolution "Duplicate"

[doctrinebot]

Comment created by @doctrinebot:

A related Github Pull-Request [GH-1558] was merged:
#1558