Removing duplicate entries from CHANGELOG (#18233)

CHANGELOG.next.asciidoc

@@ -83,7 +83,6 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Fix Elasticsearch license endpoint URL referenced in error message. {issue}17880[17880] {pull}18030[18030]
 - Fix panic when assigning a key to a `nil` value in an event. {pull}18143[18143]
 - Gives monitoring reporter hosts, if configured, total precedence over corresponding output hosts. {issue}17937[17937] {pull}17991[17991]
-- Arbitrary fields and metadata maps are now deep merged into event. {pull}17958[17958]
 - Change `decode_json_fields` processor, to merge parsed json objects with existing objects in the event instead of fully replacing them. {pull}17958[17958]
 
 *Auditbeat*
@@ -306,7 +305,6 @@ https://github.com/elastic/beats/compare/v7.0.0-alpha2...master[Check the HEAD d
 - Added an input option `publisher_pipeline.disable_host` to disable `host.name`
   from being added to events by default. {pull}18159[18159]
 - Improve ECS categorization field mappings in system module. {issue}16031[16031] {pull}18065[18065]
-- When using the `json.*` setting available on some inputs, decoded fields are now deep-merged into existing event. {pull}17958[17958]
 - Change the `json.*` input settings implementation to merge parsed json objects with existing objects in the event instead of fully replacing them. {pull}17958[17958]
 - Improve ECS categorization field mappings in osquery module. {issue}16176[16176] {pull}17881[17881]