Remove test references to py2.7 (#3076)

Author: rli

jetbrains-core/tst/software/aws/toolkits/jetbrains/services/cloudformation/CloudFormationTemplateIndexTest.kt

@@ -233,7 +233,7 @@ Resources:
             """
 Globals:
     Function:
-        Runtime: python2.7
+        Runtime: python3.9
         Handler: bar
 Resources:
   ServerlessFunction:

testdata/samProjects/image/python2.7/hello_world/Dockerfile

@@ -6149,5 +6149,5 @@ Resources:
     Properties:
       Handler: hello_world/app.lambda_handler
       CodeUri: .
-      Runtime: python2.7
+      Runtime: python3.9
       Timeout: 900