Use CAS operation to eliminate synchronized block in Sample Implementation

[guanchao-yang]

Describe

Use CAS operation to eliminate synchronized block in Sample Implementation com.alipay.common.tracer.core.samplers.SofaTracerPercentageBasedSampler

Expected behavior

Sampler don't need synchronized lock and we can use spin lock instead to avoid performance loss.

Actual behavior

We use synchronized to lock the Sampler.