pw_unit_test: Use canonical labels for group names

Use "label_no_toolchain" for group names so that the canonical GN labels
are used. Previously, group names were not formatted correctly
(//path/:target).

Change-Id: I9dc0f4637fe3ceaa16f53f2b15311dee8faebd35
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/24081
Commit-Queue: Anthony DiGirolamo <tonymd@google.com>
Reviewed-by: Anthony DiGirolamo <tonymd@google.com>
diff --git a/pw_unit_test/test.gni b/pw_unit_test/test.gni
index f7408d3..58ae9aa 100644
--- a/pw_unit_test/test.gni
+++ b/pw_unit_test/test.gni
@@ -205,7 +205,7 @@
         _group_deps_metadata += [
           {
             type = "dep"
-            group = get_path_info(dep, "abspath")
+            group = get_label_info(dep, "label_no_toolchain")
           },
         ]
       }
@@ -220,7 +220,7 @@
         self = [
           {
             type = "self"
-            name = get_path_info(":$_group_target", "abspath")
+            name = get_label_info(":$_group_target", "label_no_toolchain")
           },
         ]