Remove skylab test runner script for gtests

Skylab pipeline supports the gtest script built for chrome-on-chromeos
pipeline now. Delete the GN target to build skylab test runner script.
Meanwhile, rename generate_skylab_deps to generate_skylab_tast_filter
to reflect this change, which now only creates tast filter for tests on different CrOS images.

BUG=b/293638835

Cq-Include-Trybots: luci.chrome.try:lacros-arm64-generic-chrome-skylab
Change-Id: I6014948881853f8691d480f77498a08cc4852bb0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4791284
Commit-Queue: Xinan Lin <[email protected]>
Reviewed-by: Ben Pastene <[email protected]>
Reviewed-by: Sven Zheng <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1188032}
diff --git a/testing/test.gni b/testing/test.gni
index e583eaca..68076fc5 100644
--- a/testing/test.gni
+++ b/testing/test.gni
@@ -821,15 +821,13 @@
         "$root_out_dir/gen.runtime/" + get_label_info(target_name, "dir") +
         "/" + get_label_info(target_name, "name") + ".runtime_deps"
 
-    _generated_script = "$root_build_dir/bin/run_" + invoker.target_name
-    if (is_skylab) {
-      generate_skylab_deps(_gen_runner_target) {
-        generated_script = _generated_script
-        test_exe = invoker.target_name
+    if (is_skylab && (defined(tast_attr_expr) || defined(tast_tests) ||
+                      defined(tast_disabled_tests))) {
+      generate_skylab_tast_filter(_gen_runner_target) {
       }
     } else {
       generate_runner_script(_gen_runner_target) {
-        generated_script = _generated_script
+        generated_script = "$root_build_dir/bin/run_" + invoker.target_name
         test_exe = invoker.target_name
         runtime_deps_file = _runtime_deps_file