[UI] Remove ghost lines from background

[andersonjeccel]

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/user-documentation#...
Related developer documentation PR URL	mautic/developer-documentation-new#...
Issue(s) addressed	Fixes #...

Description

This PR removes random lines on the background.

Before:

After:

---

📋 Steps to test this PR:

1. Open this PR on Gitpod or pull down for testing locally (see docs on testing PRs here)
2. Open Assets > New > Have a look on the background

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.93%. Comparing base (4014cba) to head (2e3ed13).

Additional details and impacted files

@@             Coverage Diff              @@
##                5.x   #13785      +/-   ##
============================================
- Coverage     61.93%   61.93%   -0.01%     
  Complexity    34195    34195              
============================================
  Files          2248     2248              
  Lines        102265   102265              
============================================
- Hits          63337    63336       -1     
- Misses        38928    38929       +1     

see 1 file with indirect coverage changes

[kuzmany]

👍

[escopecz]

I wasn't able to replicate the ghost line, but I don't see this change breaking anything either 👍