[jdk11u-dev] RFR: 8285756: clean up use of bad arguments for `@clean` in langtools tests

[Aleksey Shipilev]

Clean backport to improve tests for jtreg update.

Additional testing:
 - [x] Affected tests pass with jtreg 6.2+1
 - [x] Affected tests pass with jtreg 7.3.1+1

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Commit messages:
 - Backport 3312d8c620003125a88540fd5b2bacff34732ade

Changes: https://git.openjdk.org/jdk11u-dev/pull/2555/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2555&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8285756
  Stats: 3 lines in 3 files changed: 0 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2555.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2555/head:pull/2555

PR: https://git.openjdk.org/jdk11u-dev/pull/2555