RFR: 8353727: HeapDumpPath doesn't expand %p [v2]

[Kevin Walls]

> This is a long-standing oversight: HeapDumpPath does not recognise %p for pid expansion.
> The default filename uses a pid (e.g. java_pid1676937.hprof) but HeapDumpPath does not.
> It has always done a manual "root plus pid plus extension" on the default filename only, and
> should move to using Argument::copy_expand_pid() like we do with other such filenames.
> 
> 
> We also assumed the default filename is not a directory (which is very very likely, but doesn't have to be true).

Kevin Walls has updated the pull request incrementally with two additional commits since the last revision:

 - length checking update
 - Chris feedback

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/24482/files
  - new: https://git.openjdk.org/jdk/pull/24482/files/ab82116e..c32e4ca4

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=24482&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=24482&range=00-01

  Stats: 23 lines in 2 files changed: 1 ins; 15 del; 7 mod
  Patch: https://git.openjdk.org/jdk/pull/24482.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24482/head:pull/24482

PR: https://git.openjdk.org/jdk/pull/24482