Add properties_target to Instance SW metadefs

There are several metadata definitions for software that are
associated with Nova instances (OS::Nova::Instance) which should
have their properties target set to "metadata".

The ability to add metadata to an instance leveraging these
definitions at launch time was recently added to horizon. In
a follow up discussion, somebody asked about using the metadata
definitions to also choose nova scheduler hints at launch time,
without confusing the two intended purposes of the metadata.
This raised our awareness that we don't have properties_target
set to "metadata" (rather than "scheduler hints") for
OS::Nova::Instance on the software metadata definition files.

This patch adds "properties_target": "metadata" to those files.

Change-Id: I247226ad78762d1d2add3bb39b1e780b93f36370
Closes-Bug: 1536849

etc/metadefs/software-databases.json

@@ -13,7 +13,8 @@
             "properties_target": "image"
         },
         {
-            "name": "OS::Nova::Instance"
+            "name": "OS::Nova::Instance",
+            "properties_target": "metadata"
         },
         {
             "name": "OS::Trove::Instance"

etc/metadefs/software-runtimes.json

@@ -13,7 +13,8 @@
             "properties_target": "image"
         },
         {
-            "name": "OS::Nova::Instance"
+            "name": "OS::Nova::Instance",
+            "properties_target": "metadata"
         }
     ],
     "objects": [
@@ -73,4 +74,4 @@
             }
         }
     ]
-}
+}

etc/metadefs/software-webservers.json

@@ -13,7 +13,8 @@
             "properties_target": "image"
         },
         {
-            "name": "OS::Nova::Instance"
+            "name": "OS::Nova::Instance",
+            "properties_target": "metadata"
         }
     ],
     "objects": [
@@ -99,4 +100,4 @@
             }
         }
     ]
-}
+}