RFR (T/XS) 8235808: Remove graalunit from tier1_compiler_not_xcomp

[Ekaterina Pavlova]

Please review one more issue which could result in tier1/tier3 failures.
Tier1 supposes to run only subset of graal unit tests as defined by
tier1_compiler_graal group. So compiler/graalunit were wrongly included
into tier1_compiler_not_xcomp group.


       JBS: https://bugs.openjdk.java.net/browse/JDK-8235808
    webrev: http://cr.openjdk.java.net/~epavlova//8235808/webrev.00/index.html
   testing: tier1-3 (in progress)


thanks,
-katya