RFR: 8231943: ZGC: Enable serviceability/dcmd/gc/RunGCTest

[Per Liden]

(CC:ing serviceability-dev)

On 10/7/19 2:38 PM, Per Liden wrote:
> This test is currently disabled for ZGC, but it can easily be enabled by 
> adjusting the expected log string. ZGC doesn't print "Pause Full", but 
> it still prints the "(Diagnostic Command)" part.
> 
> Also, the test enables gc=debug logging, which is unnecessary since this 
> is always printed on the gc=info level.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8231943
> Webrev: http://cr.openjdk.java.net/~pliden/8231943/webrev.0
> 
> Testing: Manually ran test with all GCs (except Epsilon)
> 
> /Per