tests: remove redundant uses of `set -e'

tests: remove redundant uses of `set -e'

* tests/deleted-am.test: Do not set the `errexit' shell flag, as
it is already set by `tests/defs'.
* tests/deleted-m4.test: Likewise.
* tests/dist-missing-am.test: Likewise.
* tests/dist-missing-am.test: Likewise.
* tests/dist-missing-m4.test: Likewise.
* tests/dist-missing-included-m4.test: Likewise.
* tests/get-sysconf.test: Likewise.
* tests/makefile-deps.test: Likewise.
* tests/remake-m4-pr10111.test: Likewise.
* tests/remake-am-pr10111.test: Likewise.
* tests/remake-deleted-am.test: Likewise.
* tests/remake-deleted-am2.test: Likewise.
* tests/remake-deleted-am-subdir.test: Likewise.
* tests/remake-renamed-am.test: Likewise.