RFR (XS) 8224119: Safepoint cleanup logging logs times for things it doesn't do

[coleen.phillimore at oracle.com]

Summary: test condition before reporting times of cleanup actions.

I only changed resizing dictionaries and purging ClassLoaderDataGraph 
(only used by CMS).  The other cleanup actions might similarly be able 
to test conditionals before reporting times when they're needed, but 
these two were obvious to me.

Ran runtime logging tests, and hs-tier1-3 testing in progress.

open webrev at http://cr.openjdk.java.net/~coleenp/2019/8224119.01/webrev
bug link https://bugs.openjdk.java.net/browse/JDK-8224119

Thanks,
Coleen