twister: restore logic to determine which gcov we should use

We do not want to use gcov from the SDK for native posix and unit tests,
instead we want the system gcov. Restore logic that determines that.

Fixes #54226

Signed-off-by: Anas Nashif <anas.nashif@intel.com>

scripts/pylib/twister/twisterlib/coverage.py

@@ -237,6 +237,10 @@ class Gcovr(CoverageTool):
 
 
 def run_coverage(testplan, options):
+    for plat in options.coverage_platform:
+        _plat = testplan.get_platform(plat)
+        if _plat and (_plat.type in {"native", "unit"}):
+            use_system_gcov = True
     if not options.gcov_tool:
         zephyr_sdk_gcov_tool = os.path.join(
             os.environ.get("ZEPHYR_SDK_INSTALL_DIR", default=""),
@@ -253,10 +257,10 @@ def run_coverage(testplan, options):
             except OSError:
                 shutil.copy(llvm_cov, gcov_lnk)
             options.gcov_tool = gcov_lnk
+        elif use_system_gcov:
+            options.gcov_tool = "gcov"
         elif os.path.exists(zephyr_sdk_gcov_tool):
             options.gcov_tool = zephyr_sdk_gcov_tool
-        else:
-            options.gcov_tool = "gcov"
 
     logger.info("Generating coverage files...")
     coverage_tool = CoverageTool.factory(options.coverage_tool)