[jdk18] RFR: 8278574: update --help-extra message to include default value of --finalization option

[Athijegannathan Sundararajan]

On Thu, 16 Dec 2021 06:33:24 GMT, Stuart Marks <smarks at openjdk.org> wrote:

> A small modification to the Launcher's help text.

LGTM

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Marked as reviewed by sundar (Reviewer).

PR: https://git.openjdk.java.net/jdk18/pull/34