Replace test usages of DigestHashFunction#getDefaultUnchecked and implicit DigestHashFunction#getDefault calls by the actual default hash function. Also remove a bunch of unnecessary Clock injections.

PiperOrigin-RevId: 330572846
diff --git a/src/test/java/com/google/devtools/build/lib/runtime/ProcessWrapperTest.java b/src/test/java/com/google/devtools/build/lib/runtime/ProcessWrapperTest.java
index b0b1a5f..d63edc7 100644
--- a/src/test/java/com/google/devtools/build/lib/runtime/ProcessWrapperTest.java
+++ b/src/test/java/com/google/devtools/build/lib/runtime/ProcessWrapperTest.java
@@ -19,6 +19,7 @@
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
 import com.google.devtools.build.lib.actions.ExecutionRequirements;
+import com.google.devtools.build.lib.vfs.DigestHashFunction;
 import com.google.devtools.build.lib.vfs.FileSystem;
 import com.google.devtools.build.lib.vfs.Path;
 import com.google.devtools.build.lib.vfs.inmemoryfs.InMemoryFileSystem;
@@ -38,7 +39,7 @@
 
   @Before
   public void setUp() {
-    testFS = new InMemoryFileSystem();
+    testFS = new InMemoryFileSystem(DigestHashFunction.SHA256);
   }
 
   private Path makeProcessWrapperBin(String path) throws IOException {