matrix-synapse: route account deactivation like current Synapse

Current Synapse still documents and registers
`/_matrix/client/.../account/deactivate` on client-serving workers when
auth is not delegated. MDAD already routes neighboring account endpoints
such as `account/3pid` and `account/whoami`, but it omitted
`account/deactivate` from both its client-reader bucket and its broader
generic-worker endpoint list.

Add the missing route patterns so MDAD's worker routing matches the
current upstream worker surface in non-delegated-auth deployments. In
MAS / MSC3861 mode the endpoint is not registered upstream anyway, so
this does not expand the effective delegated-auth surface.

Refs:
- b99a58719b/docs/workers.md (synapseappgeneric_worker)
- b99a58719b/synapse/rest/client/account.py (L284-L324)
- b99a58719b/synapse/rest/client/account.py (L913-L920)

roles/custom/matrix-synapse/vars/main.yml

@@ -31,7 +31,7 @@ matrix_synapse_workers_sync_worker_client_server_endpoints:
 
 # Client reader workers handle generic client-server endpoints that don't contain a roomid or sync
 matrix_synapse_workers_client_reader_client_server_endpoints:
-  - ^/_matrix/client/(api/v1|r0|v3|unstable)/(room_keys/|keys/(query|changes|claim|room_keys/)|login|register(/available|/m.login.registration_token/validity|)|password_policy|profile|rooms/.*/(joined_members|context/.*|members|state|hierarchy|relations/|event/|aliases|timestamp_to_event|redact|send|state/|(join|invite|leave|ban|unban|kick))|createRoom|publicRooms|account/(3pid|whoami)|versions|voip/turnServer|joined_rooms|search|user/.*/filter(/|$)|directory/room/.*|capabilities)
+  - ^/_matrix/client/(api/v1|r0|v3|unstable)/(room_keys/|keys/(query|changes|claim|room_keys/)|login|register(/available|/m.login.registration_token/validity|)|password_policy|profile|rooms/.*/(joined_members|context/.*|members|state|hierarchy|relations/|event/|aliases|timestamp_to_event|redact|send|state/|(join|invite|leave|ban|unban|kick))|createRoom|publicRooms|account/(3pid|whoami|deactivate)|versions|voip/turnServer|joined_rooms|search|user/.*/filter(/|$)|directory/room/.*|capabilities)
 
 # Federation reader workers handle generic federation endpoints that don't contain a roomid
 matrix_synapse_workers_federation_reader_federation_endpoints:
@@ -203,6 +203,7 @@ matrix_synapse_workers_generic_worker_endpoints:
   - ^/_matrix/client/unstable/im.nheko.summary/summary/.*$
   - ^/_matrix/client/(r0|v3|unstable)/account/3pid$
   - ^/_matrix/client/(r0|v3|unstable)/account/whoami$
+  - ^/_matrix/client/(r0|v3|unstable)/account/deactivate$
   - ^/_matrix/client/versions$
   - ^/_matrix/client/(api/v1|r0|v3|unstable)/voip/turnServer$
   - ^/_matrix/client/(api/v1|r0|v3|unstable)/rooms/.*/event/