maintcheck: fix more maintainer-check failures * tests/test-driver-custom-no-html.test (no-rst): Use `EOF', not `EoL', as the here-document delimiter. * tests/test-trs-basic.test: Use `cat + here-doc' rather than `echo' when creating the dummy test scripts, to please maintainer-check. * tests/test-trs-recover.test: Use creative quoting where needed, to please maintainer-check. * tests/parallel-tests-no-color-in-log.test: Likewise. * tests/parallel-tests-dry-run.test: Likewise.