Previously, the Azure blob store would depend on a 404 StorageException
coming back from Azure if trying to open an input stream to a
non-existent blob. This works for Azure repositories which access a
primary location path. For those configured to access a secondary
location path, the Azure SDK keeps trying for a long while before
returning a 404 StorageException, causing potential delays in the
snapshot APIs. This commit makes an initial check if the blob exists in
Azure and returns immediately with a NoSuchFileException, instead of
trying to open the input stream to the blob.
Closes#23480
3dff0d0de2