RFR: 8284: Fix Jolokia discovery issues

[Martin Skarsaune]

This fixes two bugs with Jolokia discovery:
1. serious : repeated discovery runs crash. Runing repeatedly in the background is the whole point
2. more of an annoyance: the PR disables JMC agent by omitting JVM info in the descriptor (as presence is interpreted as a local JVM)
Both tested OK.

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Commit messages:
 - reverted file that was committed by error
 - Remove JVM info on discovered Jolokia VMs in order to disable JMC Agent functionality
 - Fix bug where repeated runs of discovery crashes (kind of a showstopper)

Changes: https://git.openjdk.org/jmc/pull/597/files
  Webrev: https://webrevs.openjdk.org/?repo=jmc&pr=597&range=00
  Issue: https://bugs.openjdk.org/browse/JMC-8284
  Stats: 115 lines in 2 files changed: 3 ins; 105 del; 7 mod
  Patch: https://git.openjdk.org/jmc/pull/597.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/597/head:pull/597

PR: https://git.openjdk.org/jmc/pull/597