Add a request timeout to the S3 downloader during the restore

As  sandra.romanchenko suggests currently with no timeout for the S3 download request we could have situations when connection being dropped, but due to keepalive PBM would wait 2/3 hours (or longer - depends on keepalive settings) to actually retry/reconnect. 

For PBM-555 testing we set S3 session timeout 10 sec and lower and everything worked fine. 

Having such timeout would save us from potential stalls for undefined amount of time due to network issues.

Should we expose it to the config? Or have just the const let's say 10sec