Remove manual service registration files and convert more JUnit assertions to AssertJ

Co-authored-by: trask <[email protected]>

Author: Copilot

consistent-sampling/src/main/resources/META-INF/services/io.opentelemetry.sdk.autoconfigure.spi.traces.ConfigurableSamplerProvider

@@ -6,7 +6,6 @@
 package io.opentelemetry.contrib.sampler.consistent;
 
 import static org.assertj.core.api.Assertions.assertThat;
-import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.api.trace.SpanKind;
@@ -63,8 +62,8 @@ private void test(SplittableRandom rng, double samplingProbability) {
                 .getUpdatedTraceState(TraceState.getDefault())
                 .get(OtelTraceState.TRACE_STATE_KEY);
         OtelTraceState traceState = OtelTraceState.parse(traceStateString);
-        assertTrue(traceState.hasValidR());
-        assertTrue(traceState.hasValidP());
+        assertThat(traceState.hasValidR()).isTrue();
+        assertThat(traceState.hasValidP()).isTrue();
         observedPvalues.merge(traceState.getP(), 1L, Long::sum);
       }
     }