fix(ui5-select): correct focus styling for read-only state

[NakataCode]

Problem:

• In sap_horizon and sap_horizon_dark themes, the read-only focused Select had a rounded outline and wrong focus color, because it inherited incorrect overrides from Input-parameters.css.

Solution:

• Override --_ui5_input_focus_outline_color and --_ui5_input_readonly_focus_border_radius in Select-parameters.css to restore the correct spec values.

Fixes #13309

[ui5-webcomponents-bot]

🧹 Preview deployment cleaned up: https://pr-13400--ui5-webcomponents.netlify.app