fix(UI): Poller and Remote server wizard render looks broken

[Thebarda]

Description

This PR fixes Poller / Remote server wizard background color.

Fixes # (issue)

Type of change

• Patch fixing an issue (non-breaking change)
• New functionality (non-breaking change)
• Breaking change (patch or feature) that might cause side effects breaking part of the Software
• Updating documentation (missing information, typo...)

Target serie

• 2.8.x
• 18.10.x
• 19.04.x
• 19.10.x
• 20.04.x (master)

How this pull request can be tested ?

• Go to Configuration > Pollers then click on the button to add poller or remote server through a wizard.
• Each steps about remoter server and poller should be surrounded by a white background color.

Checklist

• I followed the coding style guidelines provided by Centreon
• I have commented my code, especially new classes, functions or any legacy code modified. (docblock)
• I have commented my code, especially hard-to-understand areas of the PR.
• I have made corresponding changes to the documentation.
• I have rebased my development branch on the base branch (master, maintenance).

[bdauria]

@Thebarda it seems that your changes weren't pushed