RFR(XS): JDK-8176163 - [TESTBUG] Create hotspot_cds test group

[Mikhailo Seledtsov]

     Please review this simple change that groups CDS-related test sets.

     JBS: https://bugs.openjdk.java.net/browse/JDK-8176163
     Webrev: http://cr.openjdk.java.net/~mseledtsov/8176163.00/
     Testing:
          Local (Linux-x64):
              jtreg /ws/hg/10/work02/hs/hotspot/test/:hotspot_cds
          PASS

          Also running same test set via distributed test system: In 
progress


Thank you,
Misha