RFR: 8344034: Remove security manager dependency in Serialization [v6]

[Roger Riggs]

> After [JDK-8338411](https://bugs.openjdk.org/browse/JDK-8338411), Serialization implementation dependencies on SecurityManager, doPrivildged, and AccessController are removed.
> Some refactoring to cleanup the remaining code is expected.

Roger Riggs has updated the pull request incrementally with one additional commit since the last revision:

  Remove unused imports

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/22041/files
  - new: https://git.openjdk.org/jdk/pull/22041/files/8c1fc41d..054b410f

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22041&range=05
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22041&range=04-05

  Stats: 3 lines in 1 file changed: 0 ins; 3 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/22041.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22041/head:pull/22041

PR: https://git.openjdk.org/jdk/pull/22041