how to update new parent node in the middle of the postgresql ltree by some simple update SQL statement?
I just try another stupid solution:

update product_sections 
  set section_path = text2ltree('Automation_Solutionz.Test_Case_Execution.treetype') ||
                     subltree(section_path,1,nlevel(section_path)-1) 
where section_path ~ 'Automation_Solutionz.Test_Case_Execution.*'::lquery