fix: added new color bg for md-dropdown (color contrast)

[iruchipriya]

Story - CX-13386

Description

Related Issue

Motivation and Context

How Has This Been Tested?

Screenshots:

Before (If applicable):

After:

Types of changes

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to change)
• [ ] Documentation update
• [ ] Code style update (formatting, local variables)
• [ ] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] CI related changes
• [ ] Other... Please describe:

Checklist:

• [ ] My code follows the code style of this project.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [ ] I have read the CONTRIBUTING document.
• [ ] I have added tests to cover my changes.
• [ ] All new and existing tests passed.

Figma Link -

https://www.figma.com/proto/Wffl1e8djqrhezli6n1kYU/Accessibility-for-Desktop?page-id=4007%3A85143&type=design&node-id=4007-85287&viewport=-203%2C287%2C0.07&t=qVqi2s0nvB08zOpx-1&scaling=scale-down-width&starting-point-node-id=4007%3A85533

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 94.26%. Comparing base (4cae18f) to head (b9f363b).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #1616 +/- ## ========================================== + Coverage 94.16% 94.26% +0.09% ========================================== Files 134 134 Lines 19217 19217 Branches 2957 2963 +6 ========================================== + Hits 18096 18114 +18 + Misses 1121 1103 -18 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.