[11u] RFA: 8219997: [TESTBUG] Create test for JFR events in Docker container: CPU, Memory and Process Info

[Severin Gehwolf]

Please approve backporting JDK-8219997 to OpenJDK 11u. Risk minimal. It
adds testing of JFR Events in a docker environment (better coverage)
and will help getting JDK-8222299 backported (which is in Oracle JDK
11).

Diff stat:

$ hg diff -c 29816bf5d8ff --stat
 test/hotspot/jtreg/runtime/containers/docker/JfrReporter.java   |   74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 test/hotspot/jtreg/runtime/containers/docker/TestJFREvents.java |  120 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 194 insertions(+), 0 deletions(-)

Docker tests on Linux x86_64 pass with it.

Unfortunately, I cannot view/edit JDK-8219997 as it seems private.
Hence, I have no way to apply the jdk11u-fix-request label.

Thanks,
Severin