Revert "Comment update, add several helper methods"

[jdpedrie]

Reverts #1408

A configuration issue causes the REST transport to be broken. Reverting this until the gapic generator can be updated to address the issue.

Exception:

1) Google\Cloud\Container\Tests\System\ClusterManagerClientTest::testListOperations with data set #0 (Google\Cloud\Container\V1\ClusterManagerClient Object (...))
Google\ApiCore\ValidationException: Could not map bindings for google.container.v1.ClusterManager/ListOperations to any Uri template.
Bindings: Array
(
    [parent] =>
)
UriTemplates: Array
(
    [0] => /v1/{parent=projects/*/locations/*}/operations
    [1] => /v1/projects/{project_id}/zones/{zone}/operations
)

Relevant section of cluster_manager_rest_client_config.php:

            'ListOperations' => [
                'method' => 'get',
                'uriTemplate' => '/v1/{parent=projects/*/locations/*}/operations',
                'additionalBindings' => [
                    [
                        'method' => 'get',
                        'uriTemplate' => '/v1/projects/{project_id}/zones/{zone}/operations',
                    ],
                ],
                'placeholders' => [
                    'parent' => [
                        'getters' => [
                            'getParent',
                        ],
                    ]
                ],
            ],

Without placeholder mapping for the additional binding placeholders (project_id and zone), the request builder is unable to construct a request when methods are called providing project_id and zone rather than parent.

The Gapic Generator needs to be updated to include getter mapping for placeholders in additionalBinding uriTemplates.