RFR (XS) CR 8014871: Move @Contended regression tests to the same place

[Aleksey Shipilev]

Hi,

This is the trivial test movement:
  http://cr.openjdk.java.net/~shade/8014871/webrev.00/

Please review and sponsor (can provide the changeset once I know who the
reviewers are).

-Aleksey.