RFR: Reduce the number of new product flags

[Roman Kennke]

On Tue, 11 Apr 2023 12:19:38 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> Eventual upstreaming would require a CSR for every changed product flag. Not every flag we have now needs to be product, we can reduce them to be experimental.

Looks good to me. Thank you!

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Marked as reviewed by rkennke (Lead).

PR Review: https://git.openjdk.org/shenandoah/pull/251#pullrequestreview-1382917177