Remove remnants of deprecated options

Following up on #5462

src/common/services/OptionsService.ts

@@ -19,7 +19,6 @@ export const DEFAULT_OPTIONS: Readonly<Required<ITerminalOptions>> = {
   customGlyphs: true,
   drawBoldTextInBrightColors: true,
   documentOverride: null,
-  fastScrollModifier: 'alt',
   fastScrollSensitivity: 5,
   fontFamily: 'monospace',
   fontSize: 15,
@@ -49,7 +48,6 @@ export const DEFAULT_OPTIONS: Readonly<Required<ITerminalOptions>> = {
   rescaleOverlappingGlyphs: false,
   rightClickSelectsWord: isMac,
   windowOptions: {},
-  windowsMode: false,
   windowsPty: {},
   wordSeparator: ' ()[]{}\',"`',
   altClickMovesCursor: true,

src/common/services/Services.ts

@@ -234,8 +234,6 @@ export interface ITerminalOptions {
   disableStdin?: boolean;
   documentOverride?: any | null;
   drawBoldTextInBrightColors?: boolean;
-  /** @deprecated No longer supported */
-  fastScrollModifier?: 'none' | 'alt' | 'ctrl' | 'shift';
   fastScrollSensitivity?: number;
   fontSize?: number;
   fontFamily?: string;
@@ -261,7 +259,6 @@ export interface ITerminalOptions {
   smoothScrollDuration?: number;
   tabStopWidth?: number;
   theme?: ITheme;
-  windowsMode?: boolean;
   windowsPty?: IWindowsPty;
   windowOptions?: IWindowOptions;
   wordSeparator?: string;