[Release Planner] "Select service" may have better experience when selecting service

As below, typing the service name in the textbox does not trigger the search to highlight the corresponding service in the dropdown list.

Start by locating the Release Planner's “Select service” textbox and dropdown, then reproduce the issue by typing a service name. Trace the existing search and highlighting behavior; done means typing a service name highlights the corresponding service in the dropdown.

Written by the indexing model from the issue text.