RFR: 8233214: Remove runtime code not needed with CMS removed

[Coleen Phillimore]

This change removes CMS code left over for ClassLoaderData walking.
Tested with Oracle platforms tier1 and built shenandoah with no errors.

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Commit messages:
 - 8233214: Remove runtime code not needed with CMS removed

Changes: https://git.openjdk.java.net/jdk/pull/574/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=574&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8233214
  Stats: 72 lines in 6 files changed: 0 ins; 66 del; 6 mod
  Patch: https://git.openjdk.java.net/jdk/pull/574.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/574/head:pull/574

PR: https://git.openjdk.java.net/jdk/pull/574