D7 to D9 migration fails with "The "migration" plugin does not exist"

Problem/Motivation

Attempt to migrate a D7.72 site with GA 7.x-2.6 to D9.0.5.

Steps to reproduce

Use the migrate UI, or drush migrate:import d7_google_analytics_settings

Observe error message, on the CLI with Drush or in DbLog with the migrate UI

The "migration" plugin does not exist. Valid plugin IDs for Drupal\migrate\Plugin\MigratePluginManager are: block_plugin_id, block_settings, block_visibility, block_region, block_theme, d7_field_type
  _defaults, d7_field_option_translation, d7_field_instance_option_translation, d7_field_instance_settings, d7_field_instance_defaults, d7_field_settings, d6_field_type_defaults, d6_field_option_transl
  ation, d6_field_instance_option_translation, field_formatter_settings_defaults, d6_field_field_settings, field_instance_widget_settings, d6_field_instance_defaults, field_settings, process_field, fie
  ld_type, d7_field_permission_settings, d6_field_file, file_uri, filter_format_permission, filter_id, filter_settings, google_analytics_visibility_pages, google_analytics_visibility_roles, d6_imagecac
  he_actions, content_translation_enabled_setting, language_types, language_negotiation, language_domains, field_link, link_uri, urlencode, explode, download, extract, get, file_copy, entity_exists, sk
  ip_on_empty, menu_link_parent, substr, null_coalesce, static_map, migration_lookup, sub_process, format_date, route, concat, skip_row_if_not_set, log, make_unique_entity_field, flatten, machine_name,
   default_value, callback, array_build, node_complete_node_translation_lookup, node_complete_node_revision_lookup, node_complete_node_lookup, skip_on_value, default_entity_value, dom_str_replace, sing
  le_value, dom_migration_lookup, file_blob, str_replace, multiple_values, merge, transliteration, array_shift, entity_lookup, dom, dom_apply_styles, array_pop, entity_generate, node_update_7008, d6_ur
  l_alias_language, path_set_translated, search_configuration_rankings, timezone, system_update_7000, forum_vocabulary, user_langcode, profile_field_settings, user_update_8002, d6_profile_field_option_
  translation, user_update_7002, convert_tokens

Then try a drush ms d7_google_analytics_settings, and get:

------------------- ------------------------------ ----------- ------- ---------- ------------- ---------------
  Group               Migration ID                   Status      Total   Imported   Unprocessed   Last Imported
 ------------------- ------------------------------ ----------- ------- ---------- ------------- ---------------
  Default (default)   d7_google_analytics_settings   Importing   1       0          1
 ------------------- ------------------------------ ----------- ------- ---------- ------------- ---------------

Proposed resolution

Use the current plugin name in GoogleAnalyticsVisibility[Pages|Roles]::transform(), that is migration_lookup instead of migration.

Remaining tasks

User interface changes

None.

API changes

None.

Data model changes

None.