RFR: 8270341: Test serviceability/dcmd/gc/HeapDumpAllTest.java timed-out [v2]

[Chris Plummer]

> [JDK-8267666](https://bugs.openjdk.java.net/browse/JDK-8267666) added a 2nd test case, which doubles the run time of this test. As a result it occasionally times out. This change double the timeout to 240 seconds.

Chris Plummer has updated the pull request incrementally with one additional commit since the last revision:

  Delete entry, don't just comment it out.

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/4935/files
  - new: https://git.openjdk.java.net/jdk/pull/4935/files/0218344f..27b3c756

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=4935&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=4935&range=00-01

  Stats: 2 lines in 1 file changed: 0 ins; 2 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4935.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4935/head:pull/4935

PR: https://git.openjdk.java.net/jdk/pull/4935