Increase chunk_size max to 256 Mb instead of 64 Mb

[nmjacob]

Increasing the max size of the chunk from 64mb to 256mb.

Closes #23446.

[elasticmachine]

Since this is a community submitted pull request, a Jenkins build has not been kicked off automatically. Can an Elastic organization member please verify the contents of this patch and then kick off a build manually?

[nmjacob]

This is my first time doing a public repo pr, please let me know if I need to correct anything.

[rjernst]

@nmjacob Since the chunk size is already configurable, I'm not sure why a change to the default is needed. Can you explain why you think 256mb is a better default for most users? @dadoonet thoughts?

[dadoonet]

Can you explain why you think 256mb is a better default for most users?

@rjernst If you want to send to Azure repo a 1Gb file, with the current default, it will require 16 HTTP requests. With that change we can do it with 4 HTTP requests.
I expect it to be a bit faster. Just a guess though. @abeyad WDYT?

[abeyad]

Reading the documentation, it appears that 256mb would be the optimal chunk size corresponding to an Azure blob block. We haven't tested it so its an unknown, but it makes sense to go with the documented recommendation from Azure. I do think we should run tests on this against an actual Azure storage account to see if it makes a difference.

[rjernst]

If it is the recommended then +1 to change (with testing as @abeyad mentions). One thing to double check with that testing is how it performs with default settings (ie from a laptop as a new user would try it out).

[ywelsch]

superseded by #32101