Pass task log rate limit to Diego

[#182311441](https://www.pivotaltracker.com/story/show/182311441)

Co-authored-by: Matthew Kocher <[email protected]>

lib/cloud_controller/diego/task_recipe_builder.rb

@@ -26,6 +26,7 @@ def build_app_task(config, task)
           disk_mb:                          task.disk_in_mb,
           egress_rules:                     @egress_rules.running_protobuf_rules(task.app),
           log_guid:                         task.app.guid,
+          log_rate_limit_bytes_per_second:  task.log_rate_limit,
           log_source:                       TASK_LOG_SOURCE,
           max_pids:                         config.get(:diego, :pid_limit),
           memory_mb:                        task.memory_in_mb,

spec/unit/lib/cloud_controller/diego/task_recipe_builder_spec.rb

@@ -344,6 +344,7 @@ module Diego
             app: app,
             disk_in_mb: 1024,
             memory_in_mb: 2048,
+            log_rate_limit: 3072,
             sequence_id: 9
           )
         end
@@ -468,6 +469,7 @@ module Diego
             expect(result.log_guid).to eq(app.guid)
             expect(result.memory_mb).to eq(2048)
             expect(result.disk_mb).to eq(1024)
+            expect(result.log_rate_limit_bytes_per_second).to eq(3072)
             expect(result.environment_variables).to eq(lifecycle_environment_variables)
             expect(result.legacy_download_user).to eq('vcap')
             expect(result.root_fs).to eq('preloaded:potato-stack')
@@ -610,6 +612,7 @@ module Diego
 
             expect(result.disk_mb).to eq(1024)
             expect(result.memory_mb).to eq(2048)
+            expect(result.log_rate_limit_bytes_per_second).to eq(3072)
             expect(result.log_guid).to eq(app.guid)
             expect(result.privileged).to be(false)
             expect(result.egress_rules).to eq([