feat(ui): enable "TerminalBuffer" mode to solve flicker (#24512)

packages/cli/src/ui/utils/ui-sizing.test.ts

@@ -21,6 +21,7 @@ describe('ui-sizing', () => {
       (expected, width, altBuffer) => {
         const mockConfig = {
           getUseAlternateBuffer: () => altBuffer,
+          getUseTerminalBuffer: () => false,
         } as unknown as Config;
         expect(calculateMainAreaWidth(width, mockConfig)).toBe(expected);
       },