RFR: 8253433: Remove -XX:+Debugging product option

[Coleen Phillimore]

The Debugging option shouldn't be used on the command line.  There's a SuppressErrorAt option to ignore certain
asserts, if there is some situation needing that. Debugging should never be used.

Tested with tier1 tests on 4 platforms.

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Commit messages:
 - Remove Debugging option
 - 8253433: Change -XX:+Debugging from a product to a diagnostic option

Changes: https://git.openjdk.java.net/jdk/pull/434/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=434&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8253433
  Stats: 15 lines in 4 files changed: 8 ins; 4 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/434.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/434/head:pull/434

PR: https://git.openjdk.java.net/jdk/pull/434