Use transactions when required in RedisTransientStore

Theoretically needed in:

getParameters(String key)

getBlobs(String key)

remove(String key)

persistBlobs(String key, long sizeOfBlobs, List<Map<String, String>> blobInfos)

removeAllEntries()

We'll use the MULTI / EXEC commands (+ maybe WATCH).

Might want to implement a unit test simulating concurrent read / write access to blobs / parameters of a same storage entry to illustrate the need of such transactions.

Might also want to use pipelines when possible, typically when executing a Redis command inside a for statement.