Fix test clean directory deletion

[Caideyipi]

Summary

• Make EnvironmentUtils.cleanDir recursively delete test directories with retry.
• Route EnvironmentUtils.recursiveDeleteFolder through the same recursive cleanup path.
• Replace one-level/manual UT directory cleanup with recursive cleanup in ConfigurationFileUtilsTest, FileUtilsTest, PipeTaskInfoConsensusPipeTest, AbstractRepairDataTest, and PipeDataNodePluginAgentTest.
• Add coverage for nested directory cleanup.

Tests

• mvn -Ddevelocity.off=true -pl iotdb-core/datanode,iotdb-core/node-commons,iotdb-core/confignode spotless:apply
• mvn -Ddevelocity.off=true -pl iotdb-core/datanode spotless:apply
• mvn -Ddevelocity.off=true -pl iotdb-core/node-commons -Dtest=FileUtilsTest test
• mvn -Ddevelocity.off=true -pl iotdb-core/confignode -Dtest=PipeTaskInfoConsensusPipeTest test
• Not run to completion locally: mvn -Ddevelocity.off=true -pl iotdb-core/datanode -Dtest=EnvironmentUtilsTest,ConfigurationFileUtilsTest,MergeTreeSortOperatorTest test (blocked by existing datanode compilation errors around MemoryReservationManager.reserveMemoryImmediately signature mismatch).