RFR: 8358688: HttpClient: Simplify file streaming in RequestPublishers.FilePublisher [v4]

[Volkan Yazici]

> Simplifies content streaming for `HttpRequest.BodyPublishers::ofFile(Path)`, which delegates to `RequestPublishers.FilePublisher::create(Path)`. This effectively replaces all usages of `FileInputStream::new` in `HttpClient` with `Files::newInputStream(Path)`. See the JBS ticket description for the full story.
> 
> Also removing certain test files which were rendered redundant after `SecurityManager` removal. We do this in this PR, since tests were added due to touched lines.
> 
> `tier1,2` results on b5f3c8dc6f4 are attached to the ticket.

Volkan Yazici 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 six additional commits since the last revision:

 - Merge remote-tracking branch 'upstream/master' into requestPublishersDefaultFs
 - Improve comments
 - Update tests
 - Add back removed SM tests
 - Remove redundant tests
 - Remove redundant OIO usage in `RequestPublishers`

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/25662/files
  - new: https://git.openjdk.org/jdk/pull/25662/files/9fce1c3b..b01448a0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=25662&range=03
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=25662&range=02-03

  Stats: 21809 lines in 498 files changed: 17163 ins; 3210 del; 1436 mod
  Patch: https://git.openjdk.org/jdk/pull/25662.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25662/head:pull/25662

PR: https://git.openjdk.org/jdk/pull/25662