Close test.err before deleteing it

Unfortuantely, there isn't an easy way to add integration test for this specific edge case on Windows.

Fixes #20741.

Closes #20752.

PiperOrigin-RevId: 596547046
Change-Id: I4f517b161c03793329d5a4e21ec8ac4a5b53abb0

src/main/java/com/google/devtools/build/lib/exec/StandaloneTestStrategy.java

@@ -800,9 +800,12 @@ private TestAttemptResult runTestAttempt(
         // Make sure that the test.log exists.Spaw
         FileSystemUtils.touchFile(fileOutErr.getOutputPath());
       }
+      fileOutErr.close();
       // Append any error output to the test.log. This is very rare.
+      //
+      // Only write after the error output stream has been closed. Otherwise, Bazel cannot delete
+      // test.err file on Windows. See https://github.com/bazelbuild/bazel/issues/20741.
       writeOutFile(fileOutErr.getErrorPath(), fileOutErr.getOutputPath());
-      fileOutErr.close();
       if (streamed != null) {
         streamed.close();
       }