improve logging for eni attachment issues

[sparrc]

Summary

Makes the log messages a bit more readable by removing unecessary semicolons and formats the timestamp to rfc3339. Also adds full eni details whenever available, where previously we were only printing the mac address.

log messages go from this:

level=info time=2020-11-02T16:08:49Z msg="Starting ENI ack timer with duration=2m59.99997755s, ENI Attachment: task=arn:aws:ecs:us-west-1:815665286609:task/stage-us-portal-ecs/6e8b2feb312c4e25a5cb2eeda2123c8a;attachment=arn:aws:ecs:us-west-1:815665286609:attachment/86d74d88-de5d-422c-a71f-4411a3a536e8;attachmentType=task-eni;attachmentSent=false;mac=06:5a:98:fe:4f:67;status=NONE;expiresAt=2020-11-02 16:11:49.2183602 +0000 UTC m=+672.840860713" module=eniattachment.go
...
level=warn time=2020-11-02T16:11:49Z msg="Timed out waiting for ENI ack; removing ENI attachment record with MAC address: 06:5a:98:fe:4f:67" module=attach_eni_handler_common.go

to this:

level=info time=2020-11-02T16:08:49Z msg="Starting ENI ack timer with duration=2m59.99997755s, ENI Attachment: task=arn:aws:ecs:us-west-1:815665286609:task/stage-us-portal-ecs/6e8b2feb312c4e25a5cb2eeda2123c8a attachment=arn:aws:ecs:us-west-1:815665286609:attachment/86d74d88-de5d-422c-a71f-4411a3a536e8 attachmentType=task-eni;attachmentSent=false mac=06:5a:98:fe:4f:67 status=NONE expiresAt=2020-11-02T16:11:49Z" module=eniattachment.go
...
level=warn time=2020-11-02T16:11:49Z msg="Timed out waiting for ENI ack; removing ENI attachment, ENI Attachment: task=arn:aws:ecs:us-west-1:815665286609:task/stage-us-portal-ecs/6e8b2feb312c4e25a5cb2eeda2123c8a attachment=arn:aws:ecs:us-west-1:815665286609:attachment/86d74d88-de5d-422c-a71f-4411a3a536e8 attachmentType=task-eni attachmentSent=false mac=06:5a:98:fe:4f:67 status=NONE expiresAt=2020-11-02T16:11:49Z" module=attach_eni_handler_common.go

Implementation details

Testing

New tests cover the changes: no

Description for the changelog

enhancement: more informative eni attachment logs

Licensing

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.