Benchmarking tests: automatically restore Neon reuse databases, too and migrate to pg16 (#8707)

## Problem

We use a set of **Neon** reuse databases in benchmarking.yml which are
still using pg14.
Because we want to compare apples to apples and have migrated the AWS
reuse clusters to pg16 we should also use pg16 for Neon.

## Summary of changes

- Automatically restore the test databases for Neon project

.github/workflows/_benchmarking_preparation.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        platform: [ aws-rds-postgres, aws-aurora-serverless-v2-postgres ] 
+        platform: [ aws-rds-postgres, aws-aurora-serverless-v2-postgres, neon ] 
         database: [ clickbench, tpch, userexample ]
   
     env:
@@ -31,6 +31,9 @@ jobs:
       id: set-up-prep-connstr
       run: |
         case "${PLATFORM}" in
+          neon)
+            CONNSTR=${{ secrets.BENCHMARK_CAPTEST_CONNSTR }} 
+            ;;
           aws-rds-postgres)
             CONNSTR=${{ secrets.BENCHMARK_RDS_POSTGRES_CONNSTR }} 
             ;;