RFR: CODETOOLS-7903288: Remove dead code from TestManager

[Jonathan Gibbons]

Please review another simple cleanup for TestManager, removing dead code, as we head towards more interesting improvements.

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Commit messages:
 - CODETOOLS-7903288: Remove dead code from TestManager

Changes: https://git.openjdk.org/jtreg/pull/112/files
 Webrev: https://webrevs.openjdk.org/?repo=jtreg&pr=112&range=00
  Issue: https://bugs.openjdk.org/browse/CODETOOLS-7903288
  Stats: 15 lines in 2 files changed: 1 ins; 2 del; 12 mod
  Patch: https://git.openjdk.org/jtreg/pull/112.diff
  Fetch: git fetch https://git.openjdk.org/jtreg pull/112/head:pull/112

PR: https://git.openjdk.org/jtreg/pull/112