Allow getContainerByServiceName to receive serviceName without suffix (#5776)

Fixes #5773

Author: aidando73

core/src/main/java/org/testcontainers/containers/DockerComposeContainer.java

@@ -611,7 +611,8 @@ public SELF withStartupTimeout(Duration startupTimeout) {
     }
 
     public Optional<ContainerState> getContainerByServiceName(String serviceName) {
-        return Optional.ofNullable(serviceInstanceMap.get(serviceName));
+        String serviceInstantName = getServiceInstanceName(serviceName);
+        return Optional.ofNullable(serviceInstanceMap.get(serviceInstantName));
     }
 
     private void followLogs(String containerId, Consumer<OutputFrame> consumer) {

core/src/test/java/org/testcontainers/junit/DockerComposeContainerTest.java

@@ -44,6 +44,7 @@ public void testGetServicePort() {
     public void shouldRetrieveContainerByServiceName() {
         String existingServiceName = "db_1";
         Optional<ContainerState> result = environment.getContainerByServiceName(existingServiceName);
+
         assertThat(result)
             .as(String.format("Container should be found by service name %s", existingServiceName))
             .isPresent();
@@ -52,6 +53,19 @@ public void shouldRetrieveContainerByServiceName() {
             .isEqualTo(result.get().getExposedPorts());
     }
 
+    @Test
+    public void shouldRetrieveContainerByServiceNameWithoutNumberedSuffix() {
+        String existingServiceName = "db";
+        Optional<ContainerState> result = environment.getContainerByServiceName(existingServiceName);
+
+        assertThat(result)
+            .as(String.format("Container should be found by service name %s", existingServiceName))
+            .isPresent();
+        assertThat(result.get().getExposedPorts())
+            .as("Mapped port for result container was wrong, perhaps wrong container was found")
+            .isEqualTo(Collections.singletonList(3306));
+    }
+
     @Test
     public void shouldReturnEmptyResultOnNoneExistingService() {
         String notExistingServiceName = "db_256";