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