Use index name to determine if an index is for the PK

Use index name to determine if an index is for the PK

Fixed bug in Oracle dialect where indexes that contain the full set of
primary key columns would be mistaken as the primary key index itself,
which is omitted, even if there were multiples.  The check has been refined
to compare the name of the primary key constraint against the index name
itself, rather than trying to guess based on the columns present in the
index.

Fixes: #5421
Change-Id: I47c2ccdd0b13977cfd9ef249d4de06371c4fb241