RFR: 8302109: Trivial fixes to btree tests

[Leonid Mesnik]

On Thu, 9 Feb 2023 13:30:41 GMT, Coleen Phillimore <coleenp at openjdk.org> wrote:

> Please review this trivial change.  One of the btree tests claimed to be single threaded but didn't pass -t1 so was the same as btree011.  Ran tier7 that runs these tests.

Marked as reviewed by lmesnik (Reviewer).

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PR: https://git.openjdk.org/jdk/pull/12490