Drop path property from cpp filegroup modules

The value of `path` here should be a no-op in Soong's cpp compile
action. Dropping this property helps bazel migration since Bazel's
filegroup rule does not have a path property.

Test: m libnetworkstatsfactorytestjni libservice-connectivity
Bug: 297405814

Change-Id: I7879224bf6deb12417d92e9a3fa52f58fccac999

service-t/Sources.bp

@@ -20,7 +20,6 @@ filegroup {
     srcs: [
         "jni/com_android_server_net_NetworkStatsFactory.cpp",
     ],
-    path: "jni",
     visibility: [
         "//packages/modules/Connectivity:__subpackages__",
     ],
@@ -32,7 +31,6 @@ filegroup {
         "jni/com_android_server_net_NetworkStatsFactory.cpp",
         "jni/com_android_server_net_NetworkStatsService.cpp",
     ],
-    path: "jni",
     visibility: [
         "//packages/modules/Connectivity:__subpackages__",
     ],