Recent seastar update deprecated in/out streams usage pattern when a stream is default constructed early and them move-assigned with the proper one (see scylladb/seastar#3051). This PR fixes few places in Scylla that still use one.
Adopting newer seastar API, no need to backport
Closesscylladb/scylladb#26747
* github.com:scylladb/scylladb:
commitlog: Remove unused work::r stream variable
ec2_snitch: Fix indentation after previous patch
ec2_snitch: Coroutinize the aws_api_call_once()
sstable: Construct output_stream for data instantly
test: Don't reuse on-stack input stream
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