RFR: 8344855: Remove calls to SecurityManager and doPrivileged in HTTP related implementation classes in the sun.net and sun.net.www.http packages after JEP 486 integration

[Daniel Fuchs]

Some further cleaning in the legacy HTTP implementation. 
Usual removal of doPrivileged, GetPropertyAction, checkPermission, etc...

I also took the opportunity to also remove some constructors that were never called in the legacy HttpClient, and to fix some throws signatures.

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Commit messages:
 - 8344855: Remove calls to SecurityManager and doPrivileged in HTTP related implementation classes in the sun.net and sun.net.www.http packages after JEP 486 integration

Changes: https://git.openjdk.org/jdk/pull/22321/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=22321&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8344855
  Stats: 162 lines in 7 files changed: 2 ins; 114 del; 46 mod
  Patch: https://git.openjdk.org/jdk/pull/22321.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/22321/head:pull/22321

PR: https://git.openjdk.org/jdk/pull/22321