fix: update units for effectiveCacheSize and tempBuffers (#112)

These parameters need to be described in number of 8kb blocks
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/Appendix.PostgreSQL.CommonDBATasks.Parameters.html

Author: hrodmn

lib/database/index.ts

@@ -159,11 +159,11 @@ export class PgStacDatabase extends Construct {
     return {
       maxConnections: `${maxConnections}`,
       sharedBuffers: `${sharedBuffers / 8}`, // Represented in 8kb blocks
-      effectiveCacheSize: `${effectiveCacheSize}`,
+      effectiveCacheSize: `${effectiveCacheSize / 8}`, // Represented in 8kb blocks
       workMem: `${workMem}`,
       maintenanceWorkMem: `${maintenanceWorkMem}`,
       maxLocksPerTransaction: "1024",
-      tempBuffers: `${tempBuffers}`,
+      tempBuffers: `${tempBuffers / 8}`, // Represented in 8kb blocks
       seqPageCost: `${seqPageCost}`,
       randomPageCost: `${randomPageCost}`,
     };