EmrEtlRunner: recover from request timeout

[BenFradet]

We've been getting more and more request timeout from emr lately, so we need to recover from them.

RestClient::RequestTimeout: Request Timeout
                transmit at uri:classloader:/gems/rest-client-1.8.0/lib/restclient/request.rb:427
                 execute at uri:classloader:/gems/rest-client-1.8.0/lib/restclient/request.rb:176
                 execute at uri:classloader:/gems/rest-client-1.8.0/lib/restclient/request.rb:41
                    post at uri:classloader:/gems/rest-client-1.8.0/lib/restclient.rb:69
                  submit at uri:classloader:/gems/elasticity-6.0.12/lib/elasticity/aws_session.rb:29
       add_jobflow_steps at uri:classloader:/gems/elasticity-6.0.12/lib/elasticity/emr.rb:63
                add_step at uri:classloader:/gems/elasticity-6.0.12/lib/elasticity/job_flow.rb:163
            block in run at uri:classloader:/emr-etl-runner/lib/snowplow-emr-etl-runner/emr_job.rb:684
                    each at org/jruby/RubyArray.java:1801
                     run at uri:classloader:/emr-etl-runner/lib/snowplow-emr-etl-runner/emr_job.rb:683
                 send_to at uri:classloader:/gems/contracts-0.11.0/lib/contracts/method_reference.rb:43
               call_with at uri:classloader:/gems/contracts-0.11.0/lib/contracts/call_with.rb:76
block in redefine_method at uri:classloader:/gems/contracts-0.11.0/lib/contracts/method_handler.rb:138
                     run at uri:classloader:/emr-etl-runner/lib/snowplow-emr-etl-runner/runner.rb:138
                 send_to at uri:classloader:/gems/contracts-0.11.0/lib/contracts/method_reference.rb:43
               call_with at uri:classloader:/gems/contracts-0.11.0/lib/contracts/call_with.rb:76
block in redefine_method at uri:classloader:/gems/contracts-0.11.0/lib/contracts/method_handler.rb:138
                  <main> at uri:classloader:/emr-etl-runner/bin/snowplow-emr-etl-runner:41
                    load at org/jruby/RubyKernel.java:994
                  <main> at uri:classloader:/META-INF/main.rb:1
                 require at org/jruby/RubyKernel.java:970
                  (root) at uri:classloader:/META-INF/main.rb:1
                  <main> at uri:classloader:/META-INF/jruby.home/lib/ruby/stdlib/rubygems/core_ext/kernel_require.rb:1
ERROR: org.jruby.embed.EvalFailedException: (RequestTimeout) Request Timeout