test: fix names of tests marked flaky on IBM i

Correct the names of two tests that have been marked `FLAKY` on IBM i
so they will actually be marked as such by the test runner.

Refs: nodejs#41812
Refs: nodejs#39683

PR-URL: nodejs#41984
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Mestery <mestery@protonmail.com>
Reviewed-By: Beth Griggs <bgriggs@redhat.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>

test/parallel/parallel.status

@@ -67,5 +67,5 @@ test-http-client-parse-error: PASS, FLAKY
 test-http-multi-line-headers: PASS, FLAKY
 test-http-server-unconsume: PASS, FLAKY
 test-http-upgrade-advertise: PASS, FLAKY
-test-http-client-mindhsize: PASS, FLAKY
-test-http-tls-write-error: PASS, FLAKY
+test-tls-client-mindhsize: PASS, FLAKY
+test-tls-write-error: PASS, FLAKY