tests: prevent multiple retries quickly after each other (#268)

Author: olavloite

google-cloud-spanner/src/test/java/com/google/cloud/spanner/InstanceAdminGaxTest.java

@@ -224,10 +224,10 @@ public void setUp() throws Exception {
     RetrySettings retrySettingsWithLowTimeout =
         RetrySettings.newBuilder()
             .setInitialRetryDelay(Duration.ofMillis(1L))
-            .setMaxRetryDelay(Duration.ofMillis(1L))
+            .setMaxRetryDelay(Duration.ofMillis(1000L))
             .setInitialRpcTimeout(Duration.ofMillis(20L))
             .setMaxRpcTimeout(Duration.ofMillis(200L))
-            .setRetryDelayMultiplier(1.3)
+            .setRetryDelayMultiplier(1000.0d)
             .setMaxAttempts(10)
             .setTotalTimeout(Duration.ofMillis(200L))
             .build();