chore: remove deleted guest-window-proxy.ts from CODEOWNERS (#38848)

chore: remove deleted /lib/browser/guest-window-proxy.ts from CODEOWNERS

.github/CODEOWNERS

@@ -15,6 +15,5 @@ DEPS                                    @electron/wg-upgrades
 # Security WG
 /lib/browser/devtools.ts                @electron/wg-security
 /lib/browser/guest-view-manager.ts      @electron/wg-security
-/lib/browser/guest-window-proxy.ts      @electron/wg-security
 /lib/browser/rpc-server.ts              @electron/wg-security
 /lib/renderer/security-warnings.ts      @electron/wg-security