fix: shutdown gRPC channels when close is called (#104)

* shutdown and wait for channel termination for both ScsDataGrpcStubsManager and ScsContorlGrpcStubsManager

* remove awaitTermination since it did not affect the exception throw once data channel was closed

* remove unused imports

* use try-with-resource to close instead of finally clause

* fix formatting

momento-sdk/src/intTest/java/momento/sdk/BaseTestClass.java

@@ -19,9 +19,8 @@ static void beforeAll() {
   }
 
   private static void ensureTestCacheExists() {
-    SimpleCacheClient client =
-        SimpleCacheClient.builder(System.getenv("TEST_AUTH_TOKEN"), 10).build();
-    try {
+    try (SimpleCacheClient client =
+        SimpleCacheClient.builder(System.getenv("TEST_AUTH_TOKEN"), 10).build()) {
       client.createCache(System.getenv("TEST_CACHE_NAME"));
     } catch (CacheAlreadyExistsException e) {
       // do nothing. Cache already exists.

momento-sdk/src/main/java/momento/sdk/SimpleCacheClient.java

@@ -379,5 +379,6 @@ public CompletableFuture<CacheSetResponse> setAsync(String cacheName, String key
   @Override
   public void close() {
     scsControlClient.close();
+    scsDataClient.close();
   }
 }