StarlarkAction: fix reading unusedInputsList file after action execution.

RELNOTES:
PiperOrigin-RevId: 257163694
diff --git a/src/main/java/com/google/devtools/build/lib/analysis/actions/StarlarkAction.java b/src/main/java/com/google/devtools/build/lib/analysis/actions/StarlarkAction.java
index 5523b7f..197b78a 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/actions/StarlarkAction.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/actions/StarlarkAction.java
@@ -144,7 +144,12 @@
     }
     try (BufferedReader br =
         new BufferedReader(
-            new InputStreamReader(unusedInputsList.get().getPath().getInputStream(), UTF_8))) {
+            new InputStreamReader(
+                actionExecutionContext
+                    .getPathResolver()
+                    .toPath(unusedInputsList.get())
+                    .getInputStream(),
+                UTF_8))) {
       String line;
       while ((line = br.readLine()) != null) {
         line = line.trim();