test: investigate hanging failover test

Author: karenc-bq

.github/workflows/integration_tests.yml

@@ -18,9 +18,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [ "3.8", "3.11" ]
-        engine-version: [ "lts", "latest" ]
-        environment: ["mysql", "pg"]
+        python-version: [ "3.11" ]
+        engine-version: [ "latest" ]
+        environment: [ "mysql" ]
 
     steps:
       - name: 'Clone repository'
@@ -57,6 +57,7 @@ jobs:
           RDS_DB_REGION: ${{ secrets.AWS_DEFAULT_REGION }}
           AURORA_MYSQL_DB_ENGINE_VERSION: ${{ matrix.engine-version }}
           AURORA_PG_ENGINE_VERSION: ${{ matrix.engine-version }}
+          NUM_INSTANCES: 2
 
       - name: 'Archive results'
         if: always()