adding default number_of_shared to 1 for optimization

[jinesh90]

Issue #, if available:

Description of changes:
adding default number_of_shared to 1 for optimization

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[AustinTag]

Can you provide a little more context as to the previous/new behavior, and what problem this change fixes?

Also if you could detail some of the testing you did, that would be helpful.

[jinesh90]

By default, number_of_shared is 5 and when index created it occupied 5 shared , we have some case where we are creating index every day for multiple occasion.(~100 per day). now if logstash is defaulting to 5 shared then ES is creating ~100 * 5 *2 (for back up) ~1000 shared and eventually it hits upper limit and stop accepting data. so if i set this params, it will create 200 shared per day.