Remove server-side REST batch data infrastructure

With the legacy data API no longer used (see #2258), we should also remove the related server-side infrastructure for batch requests, and the data batch REST endpoint.

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Acceptance criteria

• Our batch endpoint data (defined in REST_Routes class) should be completely removed.
• The Module::get_batch_data method should be entirely removed.
• There is one usage of the above method that needs to continue to work, which is in the Analytics 4 GET:webdatastreams-batch REST datapoint. This usage should be replaced with a (much simpler) “manual” direct usage (nothing too abstracted) of the Google client library’s batch functionality. At a high-level:
  • Use with_client_defer so that requests from Module::create_data_request aren’t immediately executed but returned as request objects.
  • Use the createBatch method from the Google_Service instance to create a batch request.
  • Add the request objects to the batch.
  • Execute the batch and parse the results so that the overall response has the same format as now.
  • Restore original client defer mode.

Implementation Brief

• Edit REST_Routes class:
  • Delete data endpoint declaration in the get_routes method.
  • Delete the error_to_response method.
• Edit Module class:
  • Delete the get_batch_data method.
• Update GET:webdatastreams-batch case in the Analytics_4::create_data_request method:
  • Grab the analyticsadmin service by calling $analyticsadmin = $this->get_service( 'analyticsadmin' ).
  • Create a batch request by calling $analyticsadmin->createBatch() method.
  • Loop through property IDs in the $data['propertyIDs'] list:
    • For each propertyID create web data streams request by calling $analyticsadmin->properties_webDataStreams->listPropertiesWebDataStreams( self::normalize_property_id( $data['propertyID'] ) )
    • Add web data stream request to the batch request using add method.
  • Return a closure that executes the batch request and returns the results of the execution.
• Check the GET:webdatastreams-batch handler in the Analytics_4::parse_data_response method to make sure it returns the same results as it has been doing before.

P.S.: no need to call with_client_defer( true ) function explicitly, it will be done automatically for the GET:webdatastreams-batch endpoint.

Test Coverage

• Remove ModuleTest::test_get_batch_data test.
• Fix broken phpunit tests

Visual Regression Changes

• N/A

QA Brief

• Open your WP dashboard to a page that makes the right request e.g.http://sitekit.10uplabs.com/wp-admin/admin.php?page=googlesitekit-module-analytics&slug=analytics&reAuth=true&notification=authentication_success
• Copy the request as a curl request.
• Run it against an env in a branch where the change exists, develop after this CR is merged.
• Run it again against main branch without the change.
• Compare the two.

Changelog entry

• Remove server-side REST batch data infrastructure.

[eugene-manuilov]

@ivankruchkoff no need to update datastores. What we need to do and what is missing in IB is that we need to unwrap results similar to how it was implemented in the legacy batch request method: https://github.com/google/site-kit-wp/blob/277034cb5213feb74fed30ad3e634aba8ce93874/includes/Core/Modules/Module.php#L350-L365

In our case, we need to add a new case for the 'GET:webdatastreams-batch' datapoint to the parse_data_response method that will loop through all batch results and compose the resulting array which consists of propertyIDs as keys and web data streams arrays as values. Web data streams need to be processed in the same way as we parse web data streams for the 'GET:webdatastreams' datapoint.

[asvinb]

QA: ✅

• Disconnected Analytics module
• Switched to develop branch
• Proceeded to connect Analytics again with Devtools open
• Copied request made to /wp-json/google-site-kit/v1/modules/analytics-4/data/webdatastreams-batch as a CURL command.
• Response:

  {"281028198":[{"createTime":"2021-07-29T12:37:57.250Z","defaultUri":"https:\/\/competent-darkling.jurassic.ninja","displayName":"competent-darkling.jurassic.ninja","measurementId":"G-BKL2ZYKK0X","name":"properties\/281028198\/webDataStreams\/2723020063","updateTime":"2021-07-29T12:37:57.250Z","_id":"2723020063","_propertyID":"281028198"}]}
  

• Switced to main branch.
• Ran the same CURL command.
• Response:

  {"281028198":[{"createTime":"2021-07-29T12:37:57.250Z","defaultUri":"https:\/\/competent-darkling.jurassic.ninja","displayName":"competent-darkling.jurassic.ninja","measurementId":"G-BKL2ZYKK0X","name":"properties\/281028198\/webDataStreams\/2723020063","updateTime":"2021-07-29T12:37:57.250Z","_id":"2723020063","_propertyID":"281028198"}]}
  

• Both responses are the same.