tests: remove redundant 'set -e' calls * tests/aclocal-install-absdir.test: Do not set the 'errexit' shell flag, as it is already set by 'tests/defs'. * tests/distcheck-pr10470.test: Likewise. * tests/objext-pr10128.test: Likewise. * tests/parallel-tests-dry-run-1.test: Likewise. * tests/silent-nested-vars.test: Likewise. * tests/tar-override.test: Likewise. * tests/vala-mix.test: Likewise. * tests/vala-vpath.test: Likewise.