Deprecate an APM BBR rule (#4511)

Author: shashank-elastic

…initial_access_cross_site_scripting.toml …initial_access_cross_site_scripting.tomlrules_building_block/initial_access_cross_site_scripting.toml renamed to rules/_deprecated/initial_access_cross_site_scripting.toml rules_building_block/initial_access_cross_site_scripting.toml renamed to rules/_deprecated/initial_access_cross_site_scripting.toml

@@ -1,8 +1,9 @@
 [metadata]
 creation_date = "2023/07/12"
 integration = ["apm"]
-maturity = "production"
-updated_date = "2024/09/01"
+maturity = "deprecated"
+updated_date = "2025/03/04"
+deprecation_date = "2025/03/04"
 
 [rule]
 author = ["Elastic"]