Use all shards to upload snapshot files to S3.
By using the sharded sstables_manager_for_table
infrastructure.
Refs #22460
Quick perf comparison
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Release build, master, smp-16, mem-32GiB
Bytes: 2342880184, backup time: 9.51 s
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Release build, this PR, smp-16, mem-32GiB
Bytes: 2342891015, backup time: 1.23 s
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Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
Co-authored-by: Ernest Zaslavsky <ernest.zaslavsky@scylladb.com>
b7212620f9