Remove handling of retries by the SDK

[fbogsany]

open-telemetry/opentelemetry-specification#511

opentelemetry-ruby/sdk/lib/opentelemetry/sdk/trace/export.rb

Lines 18 to 25 in 0009ea6

	# The export operation finished with an error, but retrying may
	# succeed.
	FAILED_RETRYABLE = 1
	# The export operation finished with an error, the caller should not
	# try to export the same data again.
	FAILED_NOT_RETRYABLE = 2
	end