refactor: remove redundant ConcurrentHashMap test from StateHolderTest

StateHolder's Map-based constructor is already exercised indirectly
through RespServerContextTest.processCommandParallelExecution. Testing
JDK's ConcurrentHashMap put/get/remove semantics adds no value.

Made-with: Cursor

Author: haiyang.zhou

src/test/java/com/github/tonivade/resp/StateHolderTest.java

@@ -11,7 +11,6 @@
 import org.junit.jupiter.api.Test;
 
 import java.util.Optional;
-import java.util.concurrent.ConcurrentHashMap;
 
 class StateHolderTest {
 
@@ -54,15 +53,4 @@ void clear() {
     assertThat(state.getValue(KEY), equalTo(Optional.empty()));
   }
 
-  @Test
-  void withConcurrentHashMap() {
-    var concurrentState = new StateHolder(new ConcurrentHashMap<>());
-
-    concurrentState.putValue(KEY, VALUE);
-    assertThat(concurrentState.getValue(KEY), equalTo(Optional.of(VALUE)));
-
-    concurrentState.removeValue(KEY);
-    assertThat(concurrentState.getValue(KEY), equalTo(Optional.empty()));
-  }
-
 }