Revert "doc: update test context.assert"

This reverts commit 7ddbfe8.

PR-URL: #55344
Reviewed-By: Jake Yuesong Li <jake.yuesong@gmail.com>
Reviewed-By: Chemi Atlow <chemi@atlow.co.il>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: aduh95

doc/api/test.md

@@ -3223,7 +3223,6 @@ test('top level test', async (t) => {
 <!-- YAML
 added:
   - v22.2.0
-  - v20.15.0
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 An object containing assertion methods bound to `context`. The top-level