chore: modify test action

[skip ci]

.github/workflows/tf-acc-test.yaml

@@ -21,6 +21,13 @@ on:
         type: string
         default: '90m'
         required: true
+      test_file:
+        description: "string that determines the test file to run (default all tests)"
+        type: choice
+        options:
+          - internal/wait/postgresflexalpha/wait_test.go
+          - internal/wait/sqlserverflexbeta/wait_test.go
+        required: true
 
 jobs:
   acc_test: