Support service metadata files in subdirectories

Consider a deegree INSPIRE workspace with several WMS and WFS instances:

* workspaces/inspire/services/inspire/ad/wfs.xml
* workspaces/inspire/services/inspire/ad/wfs_metadata.xml
* workspaces/inspire/services/inspire/ad/wms.xml
* workspaces/inspire/services/inspire/ad/wms_metadata.xml
* workspaces/inspire/services/inspire/cp/wfs.xml
* workspaces/inspire/services/inspire/cp/wfs_metadata.xml
* workspaces/inspire/services/inspire/cp/wms.xml
* workspaces/inspire/services/inspire/cp/wms_metadata.xml

In the use-cas, it is important to have separate services for each inspire theme. For WMS, the GetCapabilities request returns a document with the data from the correct wms_metadata.xml. The problem is that for WFS it does not seem to use the wfs_metadata.xml from the corresponding directory. The WFS GetCapabilities document contains some default values for metadata.

Currently, when a wfs_metadata.xml is put in the directory workspaces/inspire/services/, that file is picked up by both AD and CP WFS capabilities. This patch fixes that behavior.

Note that a patch for 3.4 is not required, as this already works as expected. This is an effect of the workspace reimplementation.