Enable the pg_regress tests on staging for PG17 (#9978)

## Problem
Currently, we run the `pg_regress` tests only for PG16
However, PG17 is a part of Neon and should be tested as well 
## Summary of changes
Modified the workflow and added a patch for PG17 enabling the
`pg_regress` tests.
The problem with leftovers was solved by using branches.

.github/workflows/cloud-regress.yml

@@ -23,11 +23,14 @@ jobs:
   regress:
     env:
       POSTGRES_DISTRIB_DIR: /tmp/neon/pg_install
-      DEFAULT_PG_VERSION: 16
       TEST_OUTPUT: /tmp/test_output
       BUILD_TYPE: remote
       AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_DEV }}
       AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_KEY_DEV }}
+    strategy:
+      fail-fast: false
+      matrix:
+        pg-version: [16, 17]
 
     runs-on: us-east-2
     container:
@@ -40,9 +43,11 @@ jobs:
           submodules: true
 
       - name: Patch the test
+        env:
+          PG_VERSION: ${{matrix.pg-version}}
         run: |
-          cd "vendor/postgres-v${DEFAULT_PG_VERSION}"
-          patch -p1 < "../../compute/patches/cloud_regress_pg${DEFAULT_PG_VERSION}.patch"
+          cd "vendor/postgres-v${PG_VERSION}"
+          patch -p1 < "../../compute/patches/cloud_regress_pg${PG_VERSION}.patch"
 
       - name: Generate a random password
         id: pwgen
@@ -55,8 +60,9 @@ jobs:
       - name: Change tests according to the generated password
         env:
           DBPASS: ${{ steps.pwgen.outputs.DBPASS }}
+          PG_VERSION: ${{matrix.pg-version}}
         run: |
-          cd vendor/postgres-v"${DEFAULT_PG_VERSION}"/src/test/regress
+          cd vendor/postgres-v"${PG_VERSION}"/src/test/regress
           for fname in sql/*.sql expected/*.out; do
             sed -i.bak s/NEON_PASSWORD_PLACEHOLDER/"'${DBPASS}'"/ "${fname}"
           done
@@ -73,15 +79,29 @@ jobs:
           path: /tmp/neon/
           prefix: latest
 
+      - name: Create a new branch
+        id: create-branch
+        uses: ./.github/actions/neon-branch-create
+        with:
+          api_key: ${{ secrets.NEON_STAGING_API_KEY }}
+          project_id: ${{ vars[format('PGREGRESS_PG{0}_PROJECT_ID', matrix.pg-version)] }}
+
       - name: Run the regression tests
         uses: ./.github/actions/run-python-test-set
         with:
           build_type: ${{ env.BUILD_TYPE }}
           test_selection: cloud_regress
-          pg_version: ${{ env.DEFAULT_PG_VERSION }}
+          pg_version: ${{matrix.pg-version}}
           extra_params: -m remote_cluster
         env:
-          BENCHMARK_CONNSTR: ${{ secrets.PG_REGRESS_CONNSTR }}
+          BENCHMARK_CONNSTR: ${{steps.create-branch.outputs.dsn}}
+
+      - name: Delete branch
+        uses: ./.github/actions/neon-branch-delete
+        with:
+          api_key: ${{ secrets.NEON_STAGING_API_KEY }}
+          project_id: ${{ vars[format('PGREGRESS_PG{0}_PROJECT_ID', matrix.pg-version)] }}
+          branch_id: ${{steps.create-branch.outputs.branch_id}}
 
       - name: Create Allure report
         id: create-allure-report