Revert "Create the feature flag for leaudio_dynamic_switcher_refactor_for_broadcast"

This reverts commit c4c7182c.

Reason for revert: design was discussed and change via aosp/2890841. Remove the unused flag.

Bug: 273153850
Bug: 317776633
Test: m com.android.btservices
Change-Id: I1363563f4a8c5a080cc0d962d9bd5cc114fcef35