Add MAX_BULK_SEND_CAPACITY to bin/sam-with-env.sh

Should've been in commit 1f5b720.
However, the fact that I set a default in template.yml shielded that
commit from any actual local, dev, or prod deployment breakages.

bin/sam-with-env.sh

@@ -27,6 +27,7 @@ PARAMETER_OVERRIDES=(
   "UnsubscribeUserName=${UNSUBSCRIBE_USER_NAME:?}"
   "ReceiptRuleSetName=${RECEIPT_RULE_SET_NAME:?}"
   "SubscribersTableName=${SUBSCRIBERS_TABLE_NAME:?}"
+  "MaxBulkSendCapacity=${MAX_BULK_SEND_CAPACITY:?}"
   "InvalidRequestPath=${INVALID_REQUEST_PATH:?}"
   "AlreadySubscribedPath=${ALREADY_SUBSCRIBED_PATH:?}"
   "VerifyLinkSentPath=${VERIFY_LINK_SENT_PATH:?}"