Remove Acoustic Integration / background sync job (#896)

* Remove pysilverpop

* Remove SVG diagram of CTMS

This is outdated in more ways than just the Acoustic sync, and it's hard to edit as code.
If we need this back, we should add a mermaid diagram.

* Remove all Acoustic / background sync code

.secrets.baseline

@@ -150,15 +150,6 @@
         "line_number": 120
       }
     ],
-    "tests/unit/test_acoustic_service.py": [
-      {
-        "type": "Secret Keyword",
-        "filename": "tests/unit/test_acoustic_service.py",
-        "hashed_secret": "3c3b274d119ff5a5ec6c1e215c1cb794d9973ac1",
-        "is_verified": false,
-        "line_number": 23
-      }
-    ],
     "tests/unit/test_auth.py": [
       {
         "type": "Secret Keyword",
@@ -174,16 +165,7 @@
         "is_verified": false,
         "line_number": 229
       }
-    ],
-    "tests/unit/test_sync.py": [
-      {
-        "type": "Secret Keyword",
-        "filename": "tests/unit/test_sync.py",
-        "hashed_secret": "3c3b274d119ff5a5ec6c1e215c1cb794d9973ac1",
-        "is_verified": false,
-        "line_number": 18
-      }
     ]
   },
-  "generated_at": "2023-07-17T09:04:13Z"
+  "generated_at": "2024-04-02T16:41:56Z"
 }

README.md

@@ -3,7 +3,6 @@
 ![Status Sustain](https://img.shields.io/badge/Status-Sustain-green)
 
 *CTMS* is an internal service at Mozilla in charge of managing marketing contacts.
-It consists of a REST API and a background synchronization process.
 
 ## Usage