RFR: 8234534: Simplify CardTable code after CMS removal [v2]

[Thomas Schatzl]

> Hi,
> 
>   can I have reviews for this cleanup that removes CMS specific code from `CardTable/CardTableRS`?
> 
> Note that there is still this "conc_scan" parameter passed to the card table that affects barrier code generation, for some reason also G1 barrier code generation although it should not as `G1CardTable::scanned_concurrently()` only used for the "normal" card table. Initial attempts showed that removing this is not straightforward, causing crashes and so I left it out for [JDK-8250941](https://bugs.openjdk.java.net/browse/JDK-8260941) so that this change is solely about removing unused code.
> 
> Testing: tier1-4, some tier1-5 runs earlier (before some removal of hunks for files only containing copyright updates or newline changes)

Thomas Schatzl has updated the pull request incrementally with one additional commit since the last revision:

  kimbarret, albertnetymk review

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

Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2354/files
  - new: https://git.openjdk.java.net/jdk/pull/2354/files/5aa23d74..849c79bb

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2354&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2354&range=00-01

  Stats: 11 lines in 4 files changed: 0 ins; 6 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2354.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2354/head:pull/2354

PR: https://git.openjdk.java.net/jdk/pull/2354