patch 9.1.1438: tests: Test_breakindent_list_split() fails

patch 9.1.1438: tests: Test_breakindent_list_split() fails

Problem:  tests: Test_breakindent_list_split() fails
          (Phạm Bình An)
Solution: Always reset "&columns" and "&lines" for GUI builds
          (Aliaksei Budavei)

Ensure that "&columns" and "&lines" are always set to their
default values before calling "SetUp()", if any, for EACH
test run by a GUI build to avoid yet-to-be-run tests from
inheriting possibly changed values (after window resizing)
and leading to broken assumptions about available estate and
occasional test failures.

fixes: #17453
closes: #17447

Signed-off-by: Aliaksei Budavei <0x000c70@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>