Default CancellationTokens start at option creation instead of when requests are sent

In the Management APIs, when neither a Timeout or CancellationToken is set, a default token is created using the ClusterOptions.ManagementTimeout.
This starts the timer when the options are created instead of when the request is sent.

Additionally, the management APIs sending their own Http requests (All except QueryIndex) don't use the options' timeout or the default Management Timeout.
Ideally, they would use the global ClusterOptions Timeout, however it's been decided that for now the Timeout will default to the base 75s only.

Changes required
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1. Issue a CancellationToken based on the options when requests are sent
2. Change APIs' options to remove the newly issued CTS + Token. Set the backing field of the Timeout() method to a TimeSpan.
3. Create new Cts from Timeout and issue a token when the CancellationToken is None