Prepare a test script to transition of the default branch name to
'main'.
* js/default-branch-name-adjust-t5411:
t5411: finish preparing for `main` being the default branch name
t5411: adjust the remaining support files for init.defaultBranch=main
t5411: start adjusting the support files for init.defaultBranch=main
t5411: start using the default branch name "main"