remove vagrant check on old file and add migration docs

Author: rjernst

docs/reference/migration/migrate_7_0.asciidoc

@@ -28,6 +28,7 @@ Elasticsearch 6.x in order to be readable by Elasticsearch 7.x.
 * <<breaking_70_indices_changes>>
 * <<breaking_70_mappings_changes>>
 * <<breaking_70_search_changes>>
+* <<breaking_70_packaging_changes>>
 * <<breaking_70_plugins_changes>>
 * <<breaking_70_analysis_changes>>
 * <<breaking_70_api_changes>>
@@ -41,6 +42,7 @@ include::migrate_7_0/cluster.asciidoc[]
 include::migrate_7_0/indices.asciidoc[]
 include::migrate_7_0/mappings.asciidoc[]
 include::migrate_7_0/search.asciidoc[]
+include::migrate_7_0/packaging.asciidoc[]
 include::migrate_7_0/plugins.asciidoc[]
 include::migrate_7_0/api.asciidoc[]
 include::migrate_7_0/java.asciidoc[]

docs/reference/migration/migrate_7_0/packaging.asciidoc

@@ -0,0 +1,9 @@
+[[breaking_70_packaging_changes]]
+=== Packaging changes
+
+==== systemd service file is no longer configuration
+
+The systemd service file `/usr/lib/systemd/system/elasticsearch.service`
+was previously marked as a configuration file in rpm and deb packages.
+Overrides to the systemd elasticsearch service should be made
+in `/etc/systemd/system/elasticsearch.service.d/override.conf`.

qa/vagrant/src/test/resources/packaging/tests/30_deb_package.bats

@@ -161,7 +161,6 @@ setup() {
 
     # The service files are still here
     assert_file_exist "/etc/init.d/elasticsearch"
-    assert_file_exist "/usr/lib/systemd/system/elasticsearch.service"
 }
 
 @test "[DEB] purge package" {