run-tests: focus on listing the selected test for the shard tests stable

run-tests: focus on listing the selected test for the shard tests

We don't care about actually running the test, but we care about what is
selected and the stability of it. So we focus on using `--list-tests` to easily
compare any changes that might happens.

--- a/tests/test-run-tests.t	Sun Nov 10 00:46:44 2024 +0100
+++ b/tests/test-run-tests.t	Mon Nov 11 11:13:34 2024 +0100
@@ -2107,91 +2107,15 @@
   usage: run-tests.py [options] [tests]
   run-tests.py: error: --shard-index must be <= than --shard-total (10 not in [1,5])
   [2]
-  $ rt --shard-index 1 --shard-total 5
-  running 3 tests using 1 parallel processes 
-  s
-  --- $TESTTMP/anothertests/cases/test-conditional-matching.t
-  +++ $TESTTMP/anothertests/cases/test-conditional-matching.t#foo.err
-  @@ -3,11 +3,14 @@
-     richtig \(true !\) (re)
-     $ echo falsch
-     falsch \(false !\) (re)
-  +  falsch
-   #if foo
-     $ echo arthur
-     arthur \(bar !\) (re)
-  +  arthur
-   #endif
-     $ echo celeste
-     celeste \(foo !\) (re)
-     $ echo zephir
-     zephir \(bar !\) (re)
-  +  zephir
-  
-  ERROR: test-conditional-matching.t#foo output changed
-  !
-  --- $TESTTMP/anothertests/cases/test-cases-advanced-cases.t
-  +++ $TESTTMP/anothertests/cases/test-cases-advanced-cases.t#case-with-dashes.err
-  @@ -1,3 +1,3 @@
-   #testcases simple case-with-dashes casewith_-.chars
-     $ echo $TESTCASE
-  -  simple
-  +  case-with-dashes
-  
-  ERROR: test-cases-advanced-cases.t#case-with-dashes output changed
-  !
-  Skipped test-cases-abc.t: Doesn't exist
-  Failed test-cases-advanced-cases.t#case-with-dashes: output changed
-  Failed test-conditional-matching.t#foo: output changed
-  # Ran 2 tests, 1 skipped, 2 failed.
-  python hash seed: * (glob)
-  [1]
+  $ rt --list-tests --shard-index 1 --shard-total 5
+  test-cases-abc.t
+  test-cases-advanced-cases.t#case-with-dashes
+  test-conditional-matching.t#foo
   $ rt --shard-index 6 --shard-total 5
   usage: run-tests.py [options] [tests]
   run-tests.py: error: --shard-index must be <= than --shard-total (6 not in [1,5])
   [2]
-  $ rt --shard-index 5 --shard-total 5
-  running 3 tests using 1 parallel processes 
-  
-  --- $TESTTMP/anothertests/cases/test-conditional-matching.t
-  +++ $TESTTMP/anothertests/cases/test-conditional-matching.t#bar.err
-  @@ -3,11 +3,13 @@
-     richtig \(true !\) (re)
-     $ echo falsch
-     falsch \(false !\) (re)
-  +  falsch
-   #if foo
-     $ echo arthur
-     arthur \(bar !\) (re)
-   #endif
-     $ echo celeste
-     celeste \(foo !\) (re)
-  +  celeste
-     $ echo zephir
-     zephir \(bar !\) (re)
-  
-  ERROR: test-conditional-matching.t#bar output changed
-  !
-  --- $TESTTMP/anothertests/cases/test-substitution.t
-  +++ $TESTTMP/anothertests/cases/test-substitution.t.err
-  @@ -7,3 +7,4 @@
-     $ echo lastbar
-     last$YYY$
-     $ echo foo-bar foo-baz
-  +  $XXX=bar foo-baz$
-  
-  ERROR: test-substitution.t output changed
-  !
-  --- $TESTTMP/anothertests/cases/test-py.py.out
-  +++ $TESTTMP/anothertests/cases/test-py.py.err
-  @@ -0,0 +1* @@ (glob)
-  +3.* (glob)
-  
-  ERROR: test-py.py output changed
-  !
-  Failed test-conditional-matching.t#bar: output changed
-  Failed test-py.py: output changed
-  Failed test-substitution.t: output changed
-  # Ran 3 tests, 0 skipped, 3 failed.
-  python hash seed: * (glob)
-  [1]
+  $ rt --list-tests --shard-index 5 --shard-total 5
+  test-conditional-matching.t#bar
+  test-py.py
+  test-substitution.t