BUG FIX: controller: add retry logic to controller it's unable to find resources

[gthao313]

Issue number:
close: #817

Description of changes:
There is a race condition when running ecs-migration-test because the resource comes out late and is recognized as not found resources. Add retry logics on it to avoid mistakenly error out.

Testing done:

 NAME                                                                              TYPE                               STATE                                                      PASSED                          FAILED                          SKIPPED
 x86-64-aws-ecs-1-migration-test-cluster-test-1-initial                            Test                               passed                                                          1                               0                                0
 x86-64-aws-ecs-1-migration-test-cluster-test-2-migrate                            Test                               passed                                                          2                               0                                0
 x86-64-aws-ecs-1-migration-test-cluster-test-3-migrated                           Test                               passed                                                          1                               0                                0
 x86-64-aws-ecs-1-migration-test-cluster-test-4-migrate                            Test                               passed                                                          2                               0                                0
 x86-64-aws-ecs-1-migration-test-cluster-test-5-final                              Test                               passed                                                          1                               0                                0
 x86-64-aws-ecs-1-migration-test-cluster                                           Resource                           completed
 x86-64-aws-ecs-1-migration-test-cluster-instances                                 Resource                           completed

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.