Fix replace entity with reference for detached lists for add to segment action

[kuzmany]

Q	A
Bug fix? (use the a.b branch)	[ ]
New feature/enhancement? (use the a.x branch)	[ ]
Deprecations?	[ ]
BC breaks? (use the c.x branch)	[ ]
Automated tests included?	[ ]
Related user documentation PR URL	mautic/mautic-documentation#...
Related developer documentation PR URL	mautic/developer-documentation#...
Issue(s) addressed	Fixes #...

Description:

This PR fix issue:

A new entity was found through the relationship 'Mautic\\LeadBundle\\Entity\\ListLead#list' that was not configured to cascade persist operations for entity: Mautic\\LeadBundle\\Entity\\LeadList with ID #318.

If we trace it, It's coming on the large instance on campaign action add to segment.

Steps to test this PR:

1. Open this PR on Gitpod or pull down for testing locally (see docs on testing PRs here)
2. You can tast campaign action for add/remove contat from segments
3. Otherwise code review is enought too

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (ff94aab) 58.59% compared to head (8499c5b) 58.60%.
Report is 38 commits behind head on 5.0.

Additional details and impacted files

@@            Coverage Diff            @@
##                5.0   #13244   +/-   ##
=========================================
  Coverage     58.59%   58.60%           
- Complexity    32975    32985   +10     
=========================================
  Files          2181     2183    +2     
  Lines         98735    98756   +21     
=========================================
+ Hits          57856    57878   +22     
+ Misses        40879    40878    -1     

Files	Coverage Δ
app/bundles/LeadBundle/Model/ListModel.php	62.90% <100.00%> (ø)

... and 9 files with indirect coverage changes

[escopecz]

The change makes sense and is a safer option to the original state. Thanks! 👍