8347004: vmTestbase/metaspace/shrink_grow/ShrinkGrowTest/ShrinkGrowTest.java fails with CDS disabled

Reviewed-by: phh, mbaesken
Backport-of: c8a30c2aaba04c11b70a4f74ee74452250be6e59

Author: GoeLin

test/hotspot/jtreg/vmTestbase/metaspace/shrink_grow/ShrinkGrowTest/ShrinkGrowTest.java

@@ -31,7 +31,7 @@
  * @requires vm.opt.final.ClassUnloading
  * @library /vmTestbase /test/lib
  * @run main/othervm
- *      -XX:MetaspaceSize=10m
+ *      -XX:MetaspaceSize=20m
  *      -XX:MaxMetaspaceSize=20m
  *      -Xlog:gc*:gc.log
  *      metaspace.shrink_grow.ShrinkGrowTest.ShrinkGrowTest