RFR: 8068: Move JMC 9 to JDK 17 [v6]

[Brice Dutheil]

> This PR builds atop #359 which has a number of improvement.
> * #359
> 
> It removed older platform that didn't support Java17 (see https://wiki.eclipse.org/Eclipse/Installation).
> 
> I didn't changed the agent to 17 though.

Brice Dutheil has updated the pull request incrementally with two additional commits since the last revision:

 - Correctly set core maven toolchain
 - Remove jdt.core.prefs and add toolchains lifecycle exclusion

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Changes:
  - all: https://git.openjdk.org/jmc/pull/482/files
  - new: https://git.openjdk.org/jmc/pull/482/files/4164d8af..3eea3f28

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jmc&pr=482&range=05
 - incr: https://webrevs.openjdk.org/?repo=jmc&pr=482&range=04-05

  Stats: 594 lines in 59 files changed: 67 ins; 527 del; 0 mod
  Patch: https://git.openjdk.org/jmc/pull/482.diff
  Fetch: git fetch https://git.openjdk.org/jmc.git pull/482/head:pull/482

PR: https://git.openjdk.org/jmc/pull/482