Backport changes to the release notes script.

Backport of elastic#37967 and elastic#38307.

Author: jpountz

dev-tools/es_release_notes.pl

@@ -32,7 +32,7 @@
     ">enhancement", ">bug",           ">regression",  ">upgrade"
 );
 my %Ignore = map { $_ => 1 }
-    ( ">non-issue", ">refactoring", ">docs", ">test", ">test-failure", ":Core/Build", "backport" );
+    ( ">non-issue", ">refactoring", ">docs", ">test", ">test-failure", ">test-mute", ":Core/Infra/Build", "backport" );
 
 my %Group_Labels = (
     '>breaking'      => 'Breaking changes',
@@ -48,7 +48,7 @@
 
 my %Area_Overrides = (
     ':ml'            => 'Machine Learning',
-    ':beats'         => 'Beats Plugin',
+    ':Beats'         => 'Beats Plugin',
     ':Docs'          => 'Docs Infrastructure'
 );