[migrate/1.5_to_2.4] remove vendor/plugins/chiliproject_custom_home_path

https://travis-ci.org/opf/openproject/builds/31161858
<pre>
$ git submodule init

No submodule mapping found in .gitmodules for path 'vendor/plugins/chiliproject_custom_home_path'

$ git submodule update

No submodule mapping found in .gitmodules for path 'vendor/plugins/chiliproject_custom_home_path'
</pre>