Remove more copies of a workaround for an ancient Android bug.

(followup to cl/604677493)

RELNOTES=n/a
PiperOrigin-RevId: 609415936

core/src/main/java/com/google/common/truth/AssertionErrorWithFacts.java

@@ -29,26 +29,12 @@
 final class AssertionErrorWithFacts extends AssertionError implements ErrorWithFacts {
   private final ImmutableList<Fact> facts;
 
-  /** Separate cause field, in case initCause() fails. */
-  private final @Nullable Throwable cause;
-
   AssertionErrorWithFacts(
       ImmutableList<String> messages, ImmutableList<Fact> facts, @Nullable Throwable cause) {
     super(makeMessage(messages, facts));
     this.facts = checkNotNull(facts);
 
-    this.cause = cause;
-    try {
-      initCause(cause);
-    } catch (IllegalStateException alreadyInitializedBecauseOfHarmonyBug) {
-      // See Truth.SimpleAssertionError.
-    }
-  }
-
-  @Override
-  @SuppressWarnings("UnsynchronizedOverridesSynchronized")
-  public @Nullable Throwable getCause() {
-    return cause;
+    initCause(cause);
   }
 
   @Override

core/src/main/java/com/google/common/truth/Platform.java

@@ -165,33 +165,19 @@ private static ImmutableList<String> splitLines(String s) {
   abstract static class PlatformComparisonFailure extends ComparisonFailure {
     private final String message;
 
-    /** Separate cause field, in case initCause() fails. */
-    private final @Nullable Throwable cause;
-
     PlatformComparisonFailure(
         String message, String expected, String actual, @Nullable Throwable cause) {
       super(message, expected, actual);
       this.message = message;
-      this.cause = cause;
 
-      try {
-        initCause(cause);
-      } catch (IllegalStateException alreadyInitializedBecauseOfHarmonyBug) {
-        // See Truth.SimpleAssertionError.
-      }
+      initCause(cause);
     }
 
     @Override
     public final String getMessage() {
       return message;
     }
 
-    @Override
-    @SuppressWarnings("UnsynchronizedOverridesSynchronized")
-    public final @Nullable Throwable getCause() {
-      return cause;
-    }
-
     // To avoid printing the class name before the message.
     // TODO(cpovirk): Write a test that fails without this. Ditto for SimpleAssertionError.
     @Override