RFR: 8233214: Remove runtime code not needed with CMS removed [v2]

[Coleen Phillimore]

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

Coleen Phillimore has updated the pull request incrementally with two additional commits since the last revision:

 - fix comment
 - fix comment

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/574/files
  - new: https://git.openjdk.java.net/jdk/pull/574/files/d3d781c1..b8b174f4

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=574&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=574&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 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