Sample rate override ignored when set to 0

[azaslavsky]

Issue Description

At https://github.com/search?q=repo%3Agetsentry%2Fsentry-ruby+valid_sample_rate&type=code, setting sample_rate to 0 does not work.

Reproduction Steps

This was reported to us by a downstream user of the SDK.

Expected Behavior

One should be able to set the sample rate to 0.

Actual Behavior

The sample rate override is ignored.

Ruby Version

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SDK Version

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Integration and Its Version

No response

Sentry Config

No response