There's no need for an extra blobExists() call when writing a blob to the Azure service. Azure
provides an option (with stronger consistency guarantees) on the upload method that guarantees
that the blob that's uploaded does not already exist. This saves one network roundtrip.
Relates to #19749
Similarly to what has been done in for the repository-s3 plugin, this
pull request moves the fixture test into a dedicated
repository-azure/qa/microsoft-azure-storage project.
It also exposes some environment variables which allows to execute the
integration tests against the real Azure Storage service. When the
environment variables are not defined, the integration tests are
executed using the fixture added in #29347.
Closes#29349
Tanguy Leroux
Yannick Welsch