RFR: 8344223: Remove calls to SecurityManager and doPrivileged in java.net.URLClassLoader after JEP 486 integration [v4]

[Jaikiran Pai]

> Can I please get a review of this change which proposes to remove SecurityManager related API usages from `URLClassLoader` and its related `URLClassPath`? This addresses https://bugs.openjdk.org/browse/JDK-8344223.
> 
> The `URLClassLoader.getPermissions()` method will need additional changes but that will be done as part of https://bugs.openjdk.org/browse/JDK-8343150.
> 
> I'll be opening a CSR for this change because we are removing support for the `jdk.net.URLClassPath.disableRestrictedPermissions` system property.
> 
> No new tests have been added and existing tier1, tier2 and tier3 tests continue to pass.

Jaikiran Pai has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - merge latest from master branch
 - Alan's review - fix code comment
 - merge latest from master branch
 - 8344223: Remove calls to SecurityManager and doPrivileged in java.net.URLClassLoader after JEP 486 integration

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/22233/files
  - new: https://git.openjdk.org/jdk/pull/22233/files/1c26dbf2..14664538

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=22233&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=22233&range=02-03

  Stats: 5325 lines in 283 files changed: 1839 ins; 2432 del; 1054 mod
  Patch: https://git.openjdk.org/jdk/pull/22233.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22233/head:pull/22233

PR: https://git.openjdk.org/jdk/pull/22233