RFR: 8330702: Update failure handler to don't generate Error message if cores actions are empty.

[Leonid Mesnik]

The message is generated if cores (or any other tools) section doesn't exist or is empty. However, there is no any tool for cores processing now defined. So ERROR message is generating, confusing users.
The fix is to don't print error for empty toolset which is the valid case. The message is still generate is tool is not defined to get error message in the case of miswriting.

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Commit messages:
 - 8330702

Changes: https://git.openjdk.org/jdk/pull/19470/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19470&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8330702
  Stats: 9 lines in 2 files changed: 5 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/19470.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19470/head:pull/19470

PR: https://git.openjdk.org/jdk/pull/19470