RFR: 8254599: CDS dump should not warn about hidden classes

[Yumin Qi]

Regular hidden class skipping warning in -Xshare:dump is at info log level, it is noise for a normal operation. Changed
to debug level, along the change, three test cases in dynamic dumping changed to debug log level to have original
message output.

Tests: tier1-5 in progress. Passed all local runtime/cds

-------------

Commit messages:
 - 8254599: CDS dump should not warn about hidden classes
 - Merge branch 'master' of https://github.com/openjdk/jdk
 - Merge branch 'master' of https://github.com/openjdk/jdk
 - Merge branch 'master' of https://github.com/openjdk/jdk
 - Merge remote-tracking branch 'origin/jdk-8252689'
 - 8252689: Classes are loaded from jrt:/java.base even when CDS is used
 - 8252689: Classes are loaded from jrt:/java.base even when CDS is used
 - 8252689: Classes are loaded from jrt:/java.base even when CDS is used

Changes: https://git.openjdk.java.net/jdk/pull/614/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=614&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8254599
  Stats: 5 lines in 4 files changed: 0 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/614.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/614/head:pull/614

PR: https://git.openjdk.java.net/jdk/pull/614