RFR: 8302888: containers/docker/TestJcmd.java fails when run as root under podman [v2]

[Severin Gehwolf]

> Could I please get a review of this trivial test fix? When `podman` is being used and the test is being run as root, which some of the other container tests require, the test fails because of the not-supported `--userns=keep-id` option:
> 
> 
> # id -u
> 0
> # podman run --rm -ti --userns=keep-id fedora:37
> Error: keep-id is only supported in rootless mode
> 
> 
> I propose to only add it when non-root.
> 
> Testing:
> 
> - [x] Ran the test with podman as root/regular user. Both passed. It failed before when run as root.

Severin Gehwolf has updated the pull request incrementally with one additional commit since the last revision:

  Only call getId() in the podman case

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/12673/files
  - new: https://git.openjdk.org/jdk/pull/12673/files/099231de..9974114b

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=12673&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=12673&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/12673.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12673/head:pull/12673

PR: https://git.openjdk.org/jdk/pull/12673