This commit fixes ping timeout settings inconsistencies in
ZenDiscovery. In particular, the documentation refers to the ping
timeout setting as discovery.zen.ping_timeout but the code was
ultimately using discovery.zen.ping.timeout if this was set.
This commit also changes all instances of the raw string
“discovery.zen.ping_timeout” to the constant
o.e.d.z.ZenDiscovery.SETTING_PING_TIMEOUT.
Finally, this commit removes the legacy setting
"discovery.zen.initial_ping_timeout".
Closes#6579, #9581, #9908
Until now we had a cloud-azure plugin which is providing 3 distinct features:
* discovery on Azure
* snapshot/restore on Aure
* SMB store
This commit splits the plugin by feature so people can use either one or the other or both features.
Doc is updated accordingly.