fix(secretsmanager): SecretRotation app does not set DeletionPolicy (#20901)

Internal Amazon campaigns are validating that all
`AWS::Serverless::Application` resources have `DeletionPolicy` set.

Since `AWS::Serverless::Application` is not classified as a stateful
resource by our metadata (nor could/should it be, because who knows?)
we don't benefit from the automatic support for these policies from
our model.

Instead, manually add the required `Delete` policies on the
`CfnApplication`.


----

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

Author: rix0rrr

packages/@aws-cdk/aws-docdb/test/cluster-rotation.lit.integ.snapshot/aws-cdk-docdb-cluster-rotation.template.json

@@ -672,7 +672,9 @@
      },
      "excludeCharacters": "\"@/"
     }
-   }
+   },
+   "UpdateReplacePolicy": "Delete",
+   "DeletionPolicy": "Delete"
   }
  },
  "Mappings": {

packages/@aws-cdk/aws-docdb/test/cluster-rotation.lit.integ.snapshot/cdk.out

@@ -1 +1 @@
-{"version":"17.0.0"}
+{"version":"20.0.0"}

packages/@aws-cdk/aws-docdb/test/cluster-rotation.lit.integ.snapshot/integ.json

@@ -1,7 +1,7 @@
 {
-  "version": "18.0.0",
+  "version": "20.0.0",
   "testCases": {
-    "aws-docdb/test/integ.cluster-rotation.lit": {
+    "integ.cluster-rotation.lit": {
       "stacks": [
         "aws-cdk-docdb-cluster-rotation"
       ],

packages/@aws-cdk/aws-docdb/test/cluster-rotation.lit.integ.snapshot/manifest.json

@@ -1,5 +1,5 @@
 {
-  "version": "17.0.0",
+  "version": "20.0.0",
   "artifacts": {
     "Tree": {
       "type": "cdk:tree",

packages/@aws-cdk/aws-docdb/test/cluster-rotation.lit.integ.snapshot/tree.json

@@ -8,8 +8,8 @@
         "id": "Tree",
         "path": "Tree",
         "constructInfo": {
-          "fqn": "@aws-cdk/core.Construct",
-          "version": "0.0.0"
+          "fqn": "constructs.Construct",
+          "version": "10.1.33"
         }
       },
       "aws-cdk-docdb-cluster-rotation": {

packages/@aws-cdk/aws-rds/test/cluster-rotation.lit.integ.snapshot/aws-cdk-rds-cluster-rotation.template.json

@@ -694,7 +694,9 @@
      },
      "excludeCharacters": " %+~`#$&*()|[]{}:;<>?!'/@\"\\"
     }
-   }
+   },
+   "UpdateReplacePolicy": "Delete",
+   "DeletionPolicy": "Delete"
   }
  },
  "Mappings": {

packages/@aws-cdk/aws-rds/test/cluster-rotation.lit.integ.snapshot/cdk.out

@@ -1 +1 @@
-{"version":"17.0.0"}
+{"version":"20.0.0"}

packages/@aws-cdk/aws-rds/test/cluster-rotation.lit.integ.snapshot/integ.json

@@ -1,7 +1,7 @@
 {
-  "version": "18.0.0",
+  "version": "20.0.0",
   "testCases": {
-    "aws-rds/test/integ.cluster-rotation.lit": {
+    "integ.cluster-rotation.lit": {
       "stacks": [
         "aws-cdk-rds-cluster-rotation"
       ],

packages/@aws-cdk/aws-rds/test/cluster-rotation.lit.integ.snapshot/manifest.json

@@ -1,5 +1,5 @@
 {
-  "version": "17.0.0",
+  "version": "20.0.0",
   "artifacts": {
     "Tree": {
       "type": "cdk:tree",

packages/@aws-cdk/aws-rds/test/cluster-rotation.lit.integ.snapshot/tree.json

@@ -8,8 +8,8 @@
         "id": "Tree",
         "path": "Tree",
         "constructInfo": {
-          "fqn": "@aws-cdk/core.Construct",
-          "version": "0.0.0"
+          "fqn": "constructs.Construct",
+          "version": "10.1.33"
         }
       },
       "aws-cdk-rds-cluster-rotation": {