tests: rename some tests to more expressive names, again

tests: rename some tests to more expressive names, again

* t/parallel-tests.sh: Rename ...
* t/parallel-tests-basics.sh: ... like this.
* t/parallel-tests3.sh: Rename ...
* t/parallel-tests-concurrency.sh: ... like this.
* t/parallel-tests5.sh: Rename ...
* t/parallel-tests-concurrency-2.sh: ... like this.
* t/parallel-tests6.sh: Rename ...
* t/parallel-tests-empty.sh: ... like this.  Adjust comments.
* t/parallel-tests8.sh: Rename ...
* t/parallel-tests-generated-and-distributed.sh: ... like this.
* t/parallel-tests9.sh: Rename ...
* t/parallel-tests-recheck.sh: ... like this.
* t/parallel-tests10.sh: Rename ...
* t/parallel-tests-trailing-whitespace.sh: ... like this.
* t/remake3a.sh: Rename ...
* t/remake-subdir-no-makefile.sh: ... like this.
* t/remake4.sh: Rename ...
* t/remake-not-after-make-dist.sh: ... like this.
* t/remake5.sh: Rename ...
* t/remake-maintainer-mode.sh: ... like this.
* t/remake6.sh: Rename ...
* t/remake-subdir3.sh: ... like this.
* t/remake7.sh: Rename ...
* t/remake-fail.sh: ... like this.
* t/remake11.sh: Rename ...
* t/remake-deeply-nested.sh: ... like this
* t/remake12.sh: Rename ...
* t/remake-mild-stress.sh: ... like this
* t/pr8365-remake-timing.sh: Rename ...
* t/remake-timing-bug-pr8365.sh: ... like this.
* t/list-of-tests.mk: Adjust.

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