feat: add configurable replicas and antiaffinity to gateway deployment for HA #1209

Job	Run time
Run Tests / Observability Integration Test (1.25-strict/stable)	39m 9s
Run Tests / Integration Test (1.27-strict/stable, integration)	43m 37s
Run Tests / Observability Integration Test (1.26-strict/stable)	36m 14s
Publish Charm / Generate the Charm Matrix	3s
Run Tests / Integration Test (1.27-strict/stable, integration-tls-provider)	37m 57s
Run Tests / Integration Test (1.27-strict/stable, integration-tls-secret)	39m 11s
Run Tests / Lint Code (pilot)	27s
Run Tests / Lint Code (gateway)	23s
Run Tests / Integration Test (1.30-strict/stable, integration)	42m 56s
Run Tests / Unit Test (pilot)	39s
Run Tests / Integration Test (1.30-strict/stable, integration-tls-provider)	39m 44s
Run Tests / Integration Test (1.30-strict/stable, integration-tls-secret)	37m 52s
Run Tests / Unit Test (gateway)	36s
Run Tests / Check libraries (istio-gateway) / Check libraries	23s
Run Tests / Check libraries (istio-gateway) / Lint	8s
Run Tests / Check libraries (istio-pilot) / Check libraries	36s
Run Tests / Check libraries (istio-pilot) / Lint	10s
Run Tests / Terraform (gateway) / Lint Terraform	9s
Run Tests / Terraform (pilot) / Lint Terraform	9s
Run Tests / Terraform (gateway) / Apply / Apply Terraform	5m 33s
Run Tests / Terraform (gateway) / Check / Check Terraform	8s
Run Tests / Terraform (pilot) / Apply / Apply Terraform	5m 59s
Run Tests / Terraform (pilot) / Check / Check Terraform	6s
Publish Charm / Publish Charm (./charms/istio-gateway)	13m 16s
Publish Charm / Publish Charm (./charms/istio-pilot)	17m 8s
	6h 2m 33s

Provide feedback