fix: MySQL memory overcommit + shlink OOMKill

- dbaas: MySQL requests 4Gi -> 2Gi (limits stay 4Gi) to free 6Gi
  of request capacity. Actual usage is 1-1.5Gi per instance.
- url/shlink: increase memory limit 512Mi -> 768Mi (OOMKilled)

stacks/platform/modules/dbaas/main.tf

@@ -181,7 +181,7 @@ resource "helm_release" "mysql_cluster" {
     resources = {
       requests = {
         cpu    = "250m"
-        memory = "4Gi"
+        memory = "2Gi"
       }
       limits = {
         memory = "4Gi"
@@ -216,7 +216,7 @@ resource "helm_release" "mysql_cluster" {
         name = "mysql"
         resources = {
           requests = {
-            memory = "4Gi"
+            memory = "2Gi"
             cpu    = "250m"
           }
           limits = {

stacks/url/main.tf

@@ -141,7 +141,7 @@ resource "kubernetes_deployment" "shlink" {
           # }
           resources {
             limits = {
-              memory = "512Mi"
+              memory = "768Mi"
             }
             requests = {
               cpu    = "25m"