tests: some more renames for texinfo tests

tests: some more renames for texinfo tests

* t/txinfo.sh: Rename ...
* t/txinfo-tex-dist.sh: ... like this.
* t/txinfo10.sh: Rename ...
* t/txinfo-dvi-recurs.sh: ... like this.
* t/txinfo20.sh: Rename ...
* t/txinfo-makeinfo-error-no-clobber.sh: ... like this.
* t/txinfo-setfilename-suffix-match.sh: Rename ...
* t/txinfo-setfilename-suffix-strip.sh: ... like this.
* t/txinfo-suffix-less-info.sh: Rename ...
* t/txinfo-without-info-suffix.sh: ... like this.
* t/vtexi.sh: Rename ...
* t/txinfo-vtexi.sh: ... like this.
* t/vtexi2.sh: Rename ...
* t/txinfo-vtexi2.sh: ... like this.
* t/vtexi3.sh: Rename ...
* t/txinfo-vtexi3.sh: ... like this, and adjust heading comments.
* t/vtexi4.sh: Rename ...
* t/txinfo-vtexi4.sh: ... like this, and adjust heading comments.
* t/list-of-tests.mk: Adjust.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>