why-error.md: Cleanup (#9510)

Author: oech3

util/why-error.md

@@ -1,48 +1,26 @@
 This file documents why some tests are failing:
 
 * gnu/tests/cp/preserve-gid.sh
-* gnu/tests/csplit/csplit-suppress-matched.pl
 * gnu/tests/date/date-debug.sh
-* gnu/tests/date/date-next-dow.pl
-* gnu/tests/date/date-tz.sh
 * gnu/tests/date/date.pl
-* gnu/tests/dd/direct.sh
 * gnu/tests/dd/no-allocate.sh
 * gnu/tests/dd/nocache_eof.sh
 * gnu/tests/dd/skip-seek-past-file.sh - https://github.com/uutils/coreutils/issues/7216
 * gnu/tests/dd/stderr.sh
-* gnu/tests/du/long-from-unreadable.sh - https://github.com/uutils/coreutils/issues/7217
-* gnu/tests/du/move-dir-while-traversing.sh
-* gnu/tests/expr/expr-multibyte.pl
-* gnu/tests/fmt/goal-option.sh
 * gnu/tests/fmt/non-space.sh
-* gnu/tests/head/head-elide-tail.pl
-* gnu/tests/head/head-pos.sh
 * gnu/tests/help/help-version-getopt.sh
 * gnu/tests/help/help-version.sh
-* gnu/tests/install/install-C.sh - https://github.com/uutils/coreutils/pull/7215
 * gnu/tests/ls/ls-misc.pl
 * gnu/tests/ls/stat-free-symlinks.sh
 * gnu/tests/misc/close-stdout.sh
-* gnu/tests/misc/comm.pl
 * gnu/tests/misc/nohup.sh
 * gnu/tests/numfmt/numfmt.pl - https://github.com/uutils/coreutils/issues/7219 / https://github.com/uutils/coreutils/issues/7221
 * gnu/tests/misc/stdbuf.sh - https://github.com/uutils/coreutils/issues/7072
-* gnu/tests/misc/tee.sh - https://github.com/uutils/coreutils/issues/7073
-* gnu/tests/misc/time-style.sh
 * gnu/tests/misc/tsort.pl - https://github.com/uutils/coreutils/issues/7074
 * gnu/tests/misc/write-errors.sh
-* gnu/tests/mv/hard-link-1.sh
-* gnu/tests/mv/mv-special-1.sh - https://github.com/uutils/coreutils/issues/7076
-* gnu/tests/mv/part-fail.sh
-* gnu/tests/mv/part-hardlink.sh
-* gnu/tests/od/od-N.sh
 * gnu/tests/od/od-float.sh
-* gnu/tests/printf/printf-quote.sh
 * gnu/tests/ptx/ptx-overrun.sh
 * gnu/tests/ptx/ptx.pl
-* gnu/tests/rm/empty-inacc.sh - https://github.com/uutils/coreutils/issues/7033
-* gnu/tests/rm/ir-1.sh
 * gnu/tests/rm/one-file-system.sh - https://github.com/uutils/coreutils/issues/7011
 * gnu/tests/rm/rm1.sh
 * gnu/tests/rm/rm2.sh