RFR: 7456: Remove the JDK 8 Eclipse launchers

[Alex Macdonald]

This PR addresses JMC-7456 [[0]](https://bugs.openjdk.java.net/browse/JMC-7456), in which the JDK-8 Eclipse launchers should be removed due to their incompatibility with Eclipse (as of 2020-09).

[0] https://bugs.openjdk.java.net/browse/JMC-7456

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Commit messages:
 - 7456: Remove the JDK 8 Eclipse launchers

Changes: https://git.openjdk.java.net/jmc/pull/339/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jmc&pr=339&range=00
  Issue: https://bugs.openjdk.java.net/browse/JMC-7456
  Stats: 435 lines in 4 files changed: 0 ins; 435 del; 0 mod
  Patch: https://git.openjdk.java.net/jmc/pull/339.diff
  Fetch: git fetch https://git.openjdk.java.net/jmc pull/339/head:pull/339

PR: https://git.openjdk.java.net/jmc/pull/339