Fix empty space between blocks' names when using search in blocks dialog

Problem/Motivation

When searching for a block after clicking "Add block" while having a large number of blocks available, you will see empty spaces between block names.

Steps to reproduce

Given that I have varbase layout builder installed
When I click add block and try to search for a block
Then I'll see empty spaces between blocks that match the search

Proposed resolution

Remove padding from (li) elements and add margin instead, so that when (a) element inside it is hidden it won't be taking any additional space.

Remaining tasks

• ✅ File an issue about this project
• ✅ Addition/Change/Update/Fix to this project
• ✅ Testing to ensure no regression
• ➖ Automated unit/functional testing coverage
• ➖ Developer Documentation support on feature change/addition
• ➖ User Guide Documentation support on feature change/addition
• ✅ Accessibility and Readability
• ✅ Code review from 1 Varbase core team member
• ✅ Full testing and approval
• ✅ Credit contributors
• ✅ Review with the product owner
• ✅ Update Release Notes and Update Helper on new feature change/addition
• ✅ Release Varbase 9.0.9, varbase_layout_builder-10.0.20

Varbase update type

• ✅ No Update
• ➖ Optional Update
• ➖ Forced Update
• ➖ Forced Update if Unchanged

User interface changes

• Removed empty space between blocks' names

Before the fix

After the fix

API changes

• N/A

Data model changes

• N/A

Release notes snippet

• Issue #3307036 by RedwanJamous: Fixed empty space between blocks' names when using search in blocks dialog