[storage-blob] don't parse url to assign container name in cases where container name is passed or known

[jeremymeng]

As commented at #23173 (comment), we always parse the url to get the container name. It's unnecessary when the name is passed via constructor parameter.

It is also nice to check other storage packages to see if there's similar room for improvement

[github-actions]

Hi @jeremymeng, we deeply appreciate your input into this project. Regrettably, this issue has remained unresolved for over 2 years and inactive for 30 days, leading us to the decision to close it. We've implemented this policy to maintain the relevance of our issue queue and facilitate easier navigation for new contributors. If you still believe this topic requires attention, please feel free to create a new issue, referencing this one. Thank you for your understanding and ongoing support.