templates: removes DATABASE_URI env var from with-vercel-website template .env.example (#10098)

### What?

Previously, the `with-vercel-website` template included a `DATABASE_URI`
env var in the `.env.example` file - which was unneeded.

### Why?

The `with-vercel-website` template uses a `POSTGRES_URL` env var for the
db connection string env var instead.

### How?

Removes the `DATABASE_URI` env var from the .env.example file.

Also, updates the `DATABASE_URI` db string names in the following
templates from `payloadtests` to `your-database-name` for a more generic
/ clear name:
- with-postgres
- with-vercel-mongodb
- with-vercel-postgres
- with-vercel-website

scripts/build-template-with-local-pkgs.ts

@@ -16,7 +16,7 @@ async function main() {
   const templateDir = path.resolve(dirname, '../templates')
   const templateName = process.argv[2]
   const templatePath = path.join(templateDir, templateName)
-  const databaseConnection = process.argv[3] || 'mongodb://127.0.0.1/payloadtests'
+  const databaseConnection = process.argv[3] || 'mongodb://127.0.0.1/your-database-name'
 
   console.log({
     templatePath,

scripts/generate-template-variations.ts

@@ -251,7 +251,7 @@ async function main() {
           ...process.env,
           PAYLOAD_SECRET: 'asecretsolongnotevensantacouldguessit',
           BLOB_READ_WRITE_TOKEN: 'vercel_blob_rw_TEST_asdf',
-          DATABASE_URI: process.env.POSTGRES_URL || 'postgres://localhost:5432/payloadtests',
+          DATABASE_URI: process.env.POSTGRES_URL || 'postgres://localhost:5432/your-database-name',
         },
       })
     }
@@ -315,12 +315,25 @@ async function writeEnvExample({
 
   const fileContents = envFileContents
     .split('\n')
-    .filter((e) => e)
+    .filter((l) => {
+      // Remove the unwanted PostgreSQL connection comment for "with-vercel-website"
+      if (
+        dbType === 'vercel-postgres' &&
+        (l.startsWith('# Or use a PG connection string') ||
+          l.startsWith('#DATABASE_URI=postgresql://'))
+      ) {
+        return false // Skip this line
+      }
+      return true // Keep other lines
+    })
     .map((l) => {
       if (l.startsWith('DATABASE_URI')) {
+        if (dbType === 'mongodb') {
+          l = 'MONGODB_URI=mongodb://127.0.0.1/your-database-name'
+        }
         // Use db-appropriate connection string
         if (dbType.includes('postgres')) {
-          l = 'DATABASE_URI=postgresql://127.0.0.1:5432/payloadtests'
+          l = 'DATABASE_URI=postgresql://127.0.0.1:5432/your-database-name'
         }
 
         // Replace DATABASE_URI with the correct env name if set
@@ -330,6 +343,7 @@ async function writeEnvExample({
       }
       return l
     })
+    .filter((l) => l.trim() !== '')
     .join('\n')
 
   console.log(`Writing to ${envExamplePath}`)