chore(coderd/database): remove unused UpdateChatMessageByID query (#27099)

Removes the `UpdateChatMessageByID` query. Its only non-generated
reference was its own dbauthz coverage test, so it is dead code.

> Generated by Coder Agents on behalf of @johnstcn.

coderd/database/queries.sql.go

@@ -11644,55 +11644,6 @@ func (q *sqlQuerier) UpdateChatMCPServerIDs(ctx context.Context, arg UpdateChatM
 	return i, err
 }
 
-const updateChatMessageByID = `-- name: UpdateChatMessageByID :one
-UPDATE
-    chat_messages
-SET
-    model_config_id = COALESCE($1::uuid, model_config_id),
-    content = $2::jsonb
-WHERE
-    id = $3::bigint
-RETURNING
-    id, chat_id, model_config_id, created_at, role, content, visibility, input_tokens, output_tokens, total_tokens, reasoning_tokens, cache_creation_tokens, cache_read_tokens, context_limit, compressed, created_by, content_version, total_cost_micros, runtime_ms, deleted, provider_response_id, api_key_id, revision
-`
-
-type UpdateChatMessageByIDParams struct {
-	ModelConfigID uuid.NullUUID         `db:"model_config_id" json:"model_config_id"`
-	Content       pqtype.NullRawMessage `db:"content" json:"content"`
-	ID            int64                 `db:"id" json:"id"`
-}
-
-func (q *sqlQuerier) UpdateChatMessageByID(ctx context.Context, arg UpdateChatMessageByIDParams) (ChatMessage, error) {
-	row := q.db.QueryRowContext(ctx, updateChatMessageByID, arg.ModelConfigID, arg.Content, arg.ID)
-	var i ChatMessage
-	err := row.Scan(
-		&i.ID,
-		&i.ChatID,
-		&i.ModelConfigID,
-		&i.CreatedAt,
-		&i.Role,
-		&i.Content,
-		&i.Visibility,
-		&i.InputTokens,
-		&i.OutputTokens,
-		&i.TotalTokens,
-		&i.ReasoningTokens,
-		&i.CacheCreationTokens,
-		&i.CacheReadTokens,
-		&i.ContextLimit,
-		&i.Compressed,
-		&i.CreatedBy,
-		&i.ContentVersion,
-		&i.TotalCostMicros,
-		&i.RuntimeMs,
-		&i.Deleted,
-		&i.ProviderResponseID,
-		&i.APIKeyID,
-		&i.Revision,
-	)
-	return i, err
-}
-
 const updateChatPinOrder = `-- name: UpdateChatPinOrder :exec
 WITH target_chat AS (
     SELECT