RFR: 8286438: Add jhsdb jstack processing without --mixed in efh

[Leonid Mesnik]

The default is required only to set the same depth level in the tree on HTML page for default and mixed mode.

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Commit messages:
 - 8286438: Add jhsdb jstack processing without --mixed in efh

Changes: https://git.openjdk.java.net/jdk/pull/8610/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8610&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8286438
  Stats: 7 lines in 1 file changed: 2 ins; 0 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8610.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8610/head:pull/8610

PR: https://git.openjdk.java.net/jdk/pull/8610