test: reduce flakiness of parallel/test-http-remove-header-stays-removed.js

The test test-http-remove-header-stays-removed.js seems to be slightly flaky as seen in https://github.com/nodejs/reliability/issues/508 and also reproducible locally by running python3 tools/test.py test/parallel/test-http-remove-header-stays-removed.js --repeat 1000

Since the test checks that the socket is closed right after receiving the last chunk of data hence moved the checking for the same after the data has been received and slightly increased the timeout, the flakiness no longer reproduces

Refs: https://github.com/nodejs/reliability/issues/508 Refs: https://github.com/nodejs/node/pull/46333