minimize test case for #2095

minimize test case for #2095

Graphviz periodically runs into problems where CI test jobs exceed the maximum
timeout and recently the project as a whole has exceeded its Gitlab CI quota.

`test_2095` is by far the longest running component of the test suite. This
change is the result of applying two test case minimizers, one clever¹ and one
not so clever², to the input to this test case. The minimizers were asked to
find smaller input that still (1) provoked a segfault on
588096bd638543ea851ea22751ed91549f61a407 and (2) could be processed successfully
on 32feee561394530713292f8873020fc5feacb9fb. The result takes a ~103KB test
input to ~5KB, with execution time in an example environment dropping from
~155s to <1s.

Gitlab: closes #2304

¹ https://github.com/googleprojectzero/halfempty
² https://github.com/Smattr/mattutils/blob/master/shrink