RFR: 7902821: Jtreg plugin fails to compile with latest Intellij (2020.3)

[Maurizio Cimadamore]

Remove @Override which caused compilation failure in latest Intellij.

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Commit messages:
 - Remove @Override which caused compilation failure in latest Intellij

Changes: https://git.openjdk.java.net/jtreg/pull/2/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jtreg&pr=2&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-7902821
  Stats: 3 lines in 2 files changed: 0 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/jtreg/pull/2.diff
  Fetch: git fetch https://git.openjdk.java.net/jtreg pull/2/head:pull/2

PR: https://git.openjdk.java.net/jtreg/pull/2