feat: make load balancer optional

[bmbferreira]

Description

This makes the usage of a load balancer completely optional since it might not be needed to access atlantis.

Motivation and Context

Currently we are forcing the usage of a load balancer associated to the ecs service. That might not be needed since the access could be provided with something like cloudflare tunnels or AWS SSM sessions to make atlantis accessible from private networks without the need of a load balancer.

Breaking Changes

How Has This Been Tested?

• I have updated at least one of the examples/* to demonstrate and validate my change(s)
• I have tested and validated these changes using one or more of the provided examples/* projects

• I have executed pre-commit run -a on my pull request

[bryantbiggs]

we already support using an external load balancer - lets start with an issue and reproduction before jumping into a PR

[bmbferreira]

we already support using an external load balancer - lets start with an issue and reproduction before jumping into a PR

hey @bryantbiggs. Thanks but what I'm trying to implement is to actually skip the load balancer entirely. As I explain on the Motivation and Context the module forces me to have a load balancer (either external or created within the module) and I don't want to have a load balancer at all, that's why I'm setting the alb_target_group_arn and alb_security_group_id as 100% optional to be able to not have a load balancer. I can put that information on an issue first if you prefer and associate with this PR. I hope I'm making myself clear but please let me know and I can add more details.

[bmbferreira]

either way, created an issue here as recommended @bryantbiggs: #410

again, hope it's clear enough. Thank you.

[github-actions]

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