test: remove outdated documentation

As noted by @richardlau, `Makefile` and `vcbuild.bat` no longer need to
be updated since they run the `default` suite.

PR-URL: #22009
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: James M Snell <jasnell@gmail.com>

test/README.md

@@ -36,7 +36,3 @@ GitHub with the `autocrlf` git config flag set to true.
 |testpy             |               |Test configuration utility used by various test suites.|
 |tick-processor     |No             |Tests for the V8 tick processor integration. The tests are for the logic in ```lib/internal/v8_prof_processor.js``` and  ```lib/internal/v8_prof_polyfill.js```. The tests confirm that the profile processor packages the correct set of scripts from V8 and introduces the correct platform specific logic.|
 |v8-updates         |No             |Tests for V8 performance integration.|
-
-_When a new test directory is added, make sure to update the `CI_JS_SUITES`
-variable in the `Makefile` and the `js_test_suites` variable in
-`vcbuild.bat`._