8367028: compiler/c2/irTests/TestFloat16ScalarOperations.java failing intermittently because of constant folding

[eme64]

The test uses random constants. But we forgot to exclude special values such as zero, otherwise the operations can be folded (idealized) and the IR tests fail. For example x + 0.42 would not be folded, but x + 0 would be folded to x.

Solution: restrict the range we sample from. Used to be [0, 1), now I just do [0.1, 0.9).

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Issue

• JDK-8367028: compiler/c2/irTests/TestFloat16ScalarOperations.java failing intermittently because of constant folding (Bug - P4)(⚠️ The fixVersion in this issue is [26] but the fixVersion in .jcheck/conf is 27, a new backport will be created when this pr is integrated.)

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