Minor tasks before releasing 3.1

[roji]

• Reenable array tests blocked by Latest builds incompatible with some PostgreSQL array scenarios dotnet/efcore#17374 (previously Reenable array operations blocked by EF Core #993)
• Reenable non-deterministic CROSS APPLY test (Fix non-deterministic CROSS APPLY tests dotnet/efcore#17379 (review), previously Reenable non-deterministic cross apply tests #994).
• Line endings (Ignore line endings in test assertions dotnet/efcore#18674)
  • GearsOfWarQueryNpgsqlTest.{Concat_with_collection_navigations,Select_navigation_with_concat_and_count}
  • SimpleQueryNpgsqlTest.{Default_if_empty_top_level_arg,Default_if_empty_top_level_arg_followed_by_projecting_constant}
  • QueryNoClientEvalNpgsqlTest.{Throws_when_join,Throws_when_group_join}
• GroupByQueryNpgsqlTest.{GroupBy_aggregate_projecting_conditional_expression,GroupBy_with_order_by_skip_and_another_order_by), depends on Fix some non-determinism in tests dotnet/efcore#18675
• ComplexNavigations{Weak,}QueryNpgsqlTest.{Include13,Include14}, depends on Apply element sorter in AssertIncludeQuery dotnet/efcore#18679
• Paging_operation_on_string_doesnt_issue_warning