fix: remove unnecessary pool_timeout parameter

Lambda handles one request per instance with connection_limit=1,
so pool contention never occurs. Removing pool_timeout as suggested
in review.

Author: konokenj

cdk/lib/constructs/database.ts

@@ -91,7 +91,6 @@ export class Database extends Construct implements ec2.IConnectable {
   public getLambdaEnvironment(databaseName: string) {
     const conn = this.getConnectionInfo();
     // connection_limit=1: Each Lambda instance handles one request at a time
-    // pool_timeout=30: Must be >= connect_timeout to allow Aurora Serverless v2 resume (~15s)
     // connect_timeout=30: Aurora Serverless v2 auto-pause resume takes ~15s (longer after 24h+ pause)
     // https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/aurora-serverless-v2-auto-pause.html
     const option = '?connection_limit=1&connect_timeout=30';

cdk/test/__snapshots__/serverless-fullstack-webapp-starter-kit-without-domain.test.ts.snap

@@ -723,7 +723,7 @@ exports[`Snapshot test 2`] = `
               ],
             },
             "DATABASE_NAME": "main",
-            "DATABASE_OPTION": "?connection_limit=1&pool_timeout=30&connect_timeout=30",
+            "DATABASE_OPTION": "?connection_limit=1&connect_timeout=30",
             "DATABASE_PASSWORD": {
               "Fn::Join": [
                 "",
@@ -772,7 +772,7 @@ exports[`Snapshot test 2`] = `
                       "Endpoint.Port",
                     ],
                   },
-                  "/main?connection_limit=1&pool_timeout=30&connect_timeout=30",
+                  "/main?connection_limit=1&connect_timeout=30",
                 ],
               ],
             },
@@ -3406,7 +3406,7 @@ service iptables save",
               ],
             },
             "DATABASE_NAME": "main",
-            "DATABASE_OPTION": "?connection_limit=1&pool_timeout=30&connect_timeout=30",
+            "DATABASE_OPTION": "?connection_limit=1&connect_timeout=30",
             "DATABASE_PASSWORD": {
               "Fn::Join": [
                 "",
@@ -3455,7 +3455,7 @@ service iptables save",
                       "Endpoint.Port",
                     ],
                   },
-                  "/main?connection_limit=1&pool_timeout=30&connect_timeout=30",
+                  "/main?connection_limit=1&connect_timeout=30",
                 ],
               ],
             },
@@ -3783,7 +3783,7 @@ service iptables save",
               ],
             },
             "DATABASE_NAME": "main",
-            "DATABASE_OPTION": "?connection_limit=1&pool_timeout=30&connect_timeout=30",
+            "DATABASE_OPTION": "?connection_limit=1&connect_timeout=30",
             "DATABASE_PASSWORD": {
               "Fn::Join": [
                 "",
@@ -3832,7 +3832,7 @@ service iptables save",
                       "Endpoint.Port",
                     ],
                   },
-                  "/main?connection_limit=1&pool_timeout=30&connect_timeout=30",
+                  "/main?connection_limit=1&connect_timeout=30",
                 ],
               ],
             },

cdk/test/__snapshots__/serverless-fullstack-webapp-starter-kit.test.ts.snap

@@ -744,7 +744,7 @@ exports[`Snapshot test 2`] = `
               ],
             },
             "DATABASE_NAME": "main",
-            "DATABASE_OPTION": "?connection_limit=1&pool_timeout=30&connect_timeout=30",
+            "DATABASE_OPTION": "?connection_limit=1&connect_timeout=30",
             "DATABASE_PASSWORD": {
               "Fn::Join": [
                 "",
@@ -793,7 +793,7 @@ exports[`Snapshot test 2`] = `
                       "Endpoint.Port",
                     ],
                   },
-                  "/main?connection_limit=1&pool_timeout=30&connect_timeout=30",
+                  "/main?connection_limit=1&connect_timeout=30",
                 ],
               ],
             },
@@ -3236,7 +3236,7 @@ service iptables save",
               ],
             },
             "DATABASE_NAME": "main",
-            "DATABASE_OPTION": "?connection_limit=1&pool_timeout=30&connect_timeout=30",
+            "DATABASE_OPTION": "?connection_limit=1&connect_timeout=30",
             "DATABASE_PASSWORD": {
               "Fn::Join": [
                 "",
@@ -3285,7 +3285,7 @@ service iptables save",
                       "Endpoint.Port",
                     ],
                   },
-                  "/main?connection_limit=1&pool_timeout=30&connect_timeout=30",
+                  "/main?connection_limit=1&connect_timeout=30",
                 ],
               ],
             },
@@ -3589,7 +3589,7 @@ service iptables save",
               ],
             },
             "DATABASE_NAME": "main",
-            "DATABASE_OPTION": "?connection_limit=1&pool_timeout=30&connect_timeout=30",
+            "DATABASE_OPTION": "?connection_limit=1&connect_timeout=30",
             "DATABASE_PASSWORD": {
               "Fn::Join": [
                 "",
@@ -3638,7 +3638,7 @@ service iptables save",
                       "Endpoint.Port",
                     ],
                   },
-                  "/main?connection_limit=1&pool_timeout=30&connect_timeout=30",
+                  "/main?connection_limit=1&connect_timeout=30",
                 ],
               ],
             },