Fix failing redeployment when the HTTP gatewayes become disabled

[amarthadan]

Based on the discussion in #1424

During the PR review for #1424 @Siegrift run into an issue where he got an error message noting a cyclic dependency in the Terraform recipes

Error: Cycle: module.httpSignedGw[0].aws_api_gateway_deployment.deployment (destroy), module.httpSignedGw[0].aws_api_gateway_rest_api.api_gateway (destroy), module.httpSignedReq[0].aws_lambda_function.lambda (destroy), module.httpSignedReq[0].null_resource.fetch_lambda_files (destroy), module.startCoordinator.aws_lambda_function.lambda

Steps to reproduce (not reliably though 😄):

1. Deploy Airnode with both HTTP gateways enabled
2. Redeploy the same Airnode (running deploy again without a removal) with one of the gateways disabled
3. Redeploy the same Airnode (running deploy again without a removal) with both of the gateways disabled

[martinkolenic]

Hi, @amarthadan, I'm happy to report that despite various combinations of gateways enabled and disabled (and then both of them disabled), the deployments have been successful so far. I'll move this to Done then :)