rename ComposableTraceIdRatioBasedSampler to ComposableProbabilitySampler

[dbarker]

Follow up to #4133

The spec defines a ComposableProbability sampler and stand alone ProbabilitySampler which replace the deprecated TraceIdRatio sampler.

The recently added ComposableTraceIdRatioBasedSampler implements the ComposableProbability sampler

Proposal:

Rename the ComposableTraceIdRatioBasedSampler to ComposableProbabilitySampler to avoid confusion and align with the spec.

[ThomsonTan]

Rename makes sense and the cost is low right now since the symbol is still unreleased, so it is better to include it in the coming release.