Fix DB connection pool test assertion for state attribute description

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

Author: Copilot

testing-common/src/main/java/io/opentelemetry/instrumentation/testing/junit/db/DbConnectionPoolMetricsAssertions.java

@@ -137,7 +137,7 @@ private void verifyUsageMetric(MetricData metric) {
     assertThat(metric)
         .hasUnit(emitStableDatabaseSemconv() ? "{connection}" : "{connections}")
         .hasDescription(
-            "The number of connections that are currently in state described by the state attribute.")
+            "The number of connections that are currently in state described by the `state` attribute.")
         .hasLongSumSatisfying(
             sum ->
                 sum.isNotMonotonic()