Dropping not from budget filter. (#18309)

Co-authored-by: Maximiliano Vera Luna <mveraluna@microsoft.com>

Author: mveraluna

specification/consumption/resource-manager/Microsoft.Consumption/stable/2021-10-01/consumption.json

@@ -4241,10 +4241,6 @@
           "x-ms-identifiers": [],
           "minItems": 0
         },
-        "not": {
-          "description": "The logical \"NOT\" expression.",
-          "$ref": "#/definitions/BudgetFilterProperties"
-        },
         "dimensions": {
           "description": "Has comparison expression for a dimension",
           "$ref": "#/definitions/BudgetComparisonExpression"