Fix #1401: rename `TreeNode.isContainerNode()` as `isContainer()` #2547

Job	Run time
build (17, ubuntu-22.04)	1m 4s
build (21, ubuntu-22.04)	57s
build (23, ubuntu-22.04)	51s
build (17, windows-latest, W)	1m 55s
Trigger downstream builds for v3	0s
Trigger downstream builds for v2	0s
	4m 47s

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