remove process handle

lib/spack/spack/install_test.py

@@ -402,6 +402,7 @@ def stand_alone_tests(self, kwargs, timeout: Optional[int] = None) -> None:
         spack.build_environment.start_build_process(
             self.pkg, test_process, kwargs, timeout=timeout
         )
+        spack.build_environment.complete_build_process()
 
     def parts(self) -> int:
         """The total number of (checked) test parts."""

lib/spack/spack/installer.py

@@ -1144,7 +1144,6 @@ def priority(self):
 class BuildTask(Task):
     """Class for representing a build task for a package."""
 
-    process_handle: Optional[spack.build_environment.ProcessHandle] = None
     started: bool = False
 
     def start(self):