Problem/Motivation
#3001496: Add an alter hook to EntityQuery added alter hooks to entity queries, but aggregate queries were forgotten.
Steps to reproduce
Implement hook_entity_query_alter() and see that aggregate queries are not invoking any hooks.
Proposed resolution
Allow aggregate entity queries to be altered.
Remaining tasks
Review.
User interface changes
Nope.
Introduced terminology
Nope.
API changes
Nope.
Data model changes
Nope.
Release notes snippet
Nope.
