switched to shutil.copy instead of subprocess copy

Author: feasel0

build/chip/chip_test_suite.gni

@@ -69,8 +69,6 @@ template("chip_test_suite") {
       invoker.sources += invoker.test_sources
     }
   }
-  #++++x did we change the logic here?  think about it for all cases that don't involve building efr32 test driver -- would should happen if chip_link_tests is true or false?
-  #   prior to me making my changes for efr32 test driver, was it was ok if the the test_sources were contained in both the common library and the individual libraries?
 
   # Target for the common library.  Contains all the common sources, and sometimes all the individual test sources.
   if (chip_build_test_static_libraries) {

scripts/flashing/silabs_firmware_utils.py

@@ -50,7 +50,7 @@
 """
 
 import os
-import subprocess
+import shutil
 import sys
 
 import firmware_utils
@@ -183,10 +183,10 @@ def _platform_wrapper_args(self, args):
             output_dir = os.path.dirname(args.output) or "."
             if args.platform_firmware_utils is not None:
                 flashbundle_contents += "\n" + os.path.basename(args.platform_firmware_utils)
-                subprocess.run(["cp", args.platform_firmware_utils, output_dir])
+                shutil.copy(args.platform_firmware_utils, output_dir)
             if args.firmware_utils is not None:
                 flashbundle_contents += "\n" + os.path.basename(args.firmware_utils)
-                subprocess.run(["cp", args.firmware_utils, output_dir])
+                shutil.copy(args.firmware_utils, output_dir)
 
             # Create the flashbundle file.
             try: