Remove the `dont_notify` and `coalesce` push rule actions. (#1501)

* Remove the `dont_notify` and `coalesce` push rule actions.

Per MSC3987, these should both be considered no-ops.

* Remove obsolete dont_notify from default rules.

* Remove obsolete dont_notify from examples.

changelogs/client_server/newsfragments/1501.clarification

@@ -0,0 +1 @@
+Remove the `dont_notify` and `coalesce` push rule actions per [MSC3987](https://github.com/matrix-org/matrix-spec-proposals/pull/3987).

content/client-server-api/modules/push.md

@@ -147,17 +147,6 @@ actions are defined:
 
 :   This causes each matching event to generate a notification.
 
-`dont_notify`
-
-:   This prevents each matching event from generating a notification.
-
-`coalesce`
-
-:   This enables notifications for matching events but activates homeserver
-    specific behaviour to intelligently coalesce multiple events into a
-    single notification. Not all homeservers may support this. Those that do
-    not support it should treat it as the `notify` action.
-
 `set_tweak`
 
 :   Sets an entry in the `tweaks` dictionary key that is sent in the
@@ -195,6 +184,12 @@ they are represented as a dictionary with a key equal to their name and
 other keys as their parameters, e.g.
 `{ "set_tweak": "sound", "value": "default" }`.
 
+{{% boxes/note %}}
+Older versions of the Matrix specification included the `dont_notify` and
+`coalesce` actions. These should both be considered no-ops (ignored, not
+rejected) if received from a client.
+{{% /boxes/note %}}
+
 ##### Conditions
 
 `override` and `underride` rules MAY have a list of 'conditions'. All
@@ -440,9 +435,7 @@ Definition:
     "default": true,
     "enabled": false,
     "conditions": [],
-    "actions": [
-        "dont_notify"
-    ]
+    "actions": []
 }
 ```
 
@@ -464,9 +457,7 @@ Definition:
             "pattern": "m.notice",
         }
     ],
-    "actions": [
-        "dont_notify",
-    ]
+    "actions": []
 }
 ```
 
@@ -526,9 +517,7 @@ Definition:
             "pattern": "m.room.member"
         }
     ],
-    "actions": [
-        "dont_notify"
-    ]
+    "actions": []
 }
 ```
 
@@ -882,14 +871,14 @@ To create a rule that suppresses notifications for the room with ID
 
     curl -X PUT -H "Content-Type: application/json" "https://example.com/_matrix/client/v3/pushrules/global/room/%21dj234r78wl45Gh4D%3Amatrix.org?access_token=123456" -d \
     '{
-       "actions" : ["dont_notify"]
+       "actions" : []
      }'
 
 To suppress notifications for the user `@spambot:matrix.org`:
 
     curl -X PUT -H "Content-Type: application/json" "https://example.com/_matrix/client/v3/pushrules/global/sender/%40spambot%3Amatrix.org?access_token=123456" -d \
     '{
-       "actions" : ["dont_notify"]
+       "actions" : []
      }'
 
 To always notify for messages that contain the work 'cake' and set a

data/api/client-server/pushrules.yaml

@@ -75,18 +75,14 @@ paths:
                     ],
                     "override": [
                         {
-                            "actions": [
-                                "dont_notify"
-                            ],
+                            "actions": [],
                             "conditions": [],
                             "default": true,
                             "enabled": false,
                             "rule_id": ".m.rule.master"
                         },
                         {
-                            "actions": [
-                                "dont_notify"
-                            ],
+                            "actions": [],
                             "conditions": [
                                 {
                                     "key": "content.msgtype",
@@ -286,9 +282,7 @@ paths:
             rule itself such as the rule's `actions` and `conditions` if set.
           examples:
             application/json: {
-                "actions": [
-                    "dont_notify"
-                ],
+                "actions": [],
                 "pattern": "cake*lie",
                 "rule_id": "nocake",
                 "enabled": true,

data/event-schemas/examples/m.push_rules.yaml

@@ -23,18 +23,14 @@
       ],
       "override": [
         {
-          "actions": [
-            "dont_notify"
-          ],
+          "actions": [],
           "conditions": [],
           "default": true,
           "enabled": false,
           "rule_id": ".m.rule.master"
         },
         {
-          "actions": [
-            "dont_notify"
-          ],
+          "actions": [],
           "conditions": [
             {
               "key": "content.msgtype",