core: increased test tolerance to 1 second

Fixes grpc#11680

Author: vinodhabib

core/src/test/java/io/grpc/internal/InstantTimeProviderTest.java

@@ -44,7 +44,7 @@ public void testInstantCurrentTimeNanos() throws Exception {
           + instantNow.getNano();
 
     // Validate the time returned is close to the expected value within a tolerance
-    // (i,e 10 millisecond tolerance in nanoseconds).
-    assertThat(actualTimeNanos).isWithin(10_000_000L).of(expectedTimeNanos);
+    // (i,e 1000 millisecond (1 second) tolerance in nanoseconds).
+    assertThat(actualTimeNanos).isWithin(1000_000_000L).of(expectedTimeNanos);
   }
 }