Use Bazel Preconditions variant which avoids varargs array creation

Reduces garbage.

--
MOS_MIGRATED_REVID=109914243
diff --git a/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java b/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java
index 96dc02a..ca7de18 100644
--- a/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java
+++ b/src/test/java/com/google/devtools/build/lib/skyframe/FileFunctionTest.java
@@ -23,7 +23,6 @@
 import static org.junit.Assert.fail;
 
 import com.google.common.base.Function;
-import com.google.common.base.Preconditions;
 import com.google.common.base.Strings;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
@@ -44,6 +43,7 @@
 import com.google.devtools.build.lib.testutil.TestUtils;
 import com.google.devtools.build.lib.util.BlazeClock;
 import com.google.devtools.build.lib.util.Pair;
+import com.google.devtools.build.lib.util.Preconditions;
 import com.google.devtools.build.lib.util.io.TimestampGranularityMonitor;
 import com.google.devtools.build.lib.vfs.FileStatus;
 import com.google.devtools.build.lib.vfs.FileSystem;