Update executeCmdWithRetry() to do with rt_code=128

[executeCmdWithRetry() in get.sh ](https://github.com/adoptium/aqa-tests/blob/master/get.sh#L468) is used to retry git if there are unexpected failures.

Running in mac locally found if the return code is 128, which says the folder exist and not empty, executeCmdWithRetry will continue to retry instead of either delete the dir or exit the command.

Start in get.sh around executeCmdWithRetry() at line 468 and inspect how git failures and return code 128 are handled. Reproduce the macOS case if possible, then confirm the intended completed behavior for a non-empty directory: remove it before retrying or stop with the command's failure.

Written by the indexing model from the issue text.