db_get_table: always append suffix

Commit 2ce60e4715ef60cb51799f274bd3db7abc2ee3a3 added a check to not
append the suffix for Oracle. This removes this because

• the test was incorrect, and caused non-Oracle installs to never have
  the suffix appended
• with recent changes to Oracle branch, where we specify a short suffix
  in the installer, this is no longer necessary.

The suffix is now systematically appended.