Use EnvAndSysPropClientProviderStrategy only if DOCKER_HOST is set (#2987)

Author: bsideup

core/src/main/java/org/testcontainers/dockerclient/EnvironmentAndSystemPropertyClientProviderStrategy.java

@@ -17,6 +17,11 @@ public final class EnvironmentAndSystemPropertyClientProviderStrategy extends Do
     // Try using environment variables
     private final DockerClientConfig dockerClientConfig = DefaultDockerClientConfig.createDefaultConfigBuilder().build();
 
+    @Override
+    protected boolean isApplicable() {
+        return System.getenv("DOCKER_HOST") != null;
+    }
+
     @Override
     public TransportConfig getTransportConfig() {
         return TransportConfig.builder()