Change in log indentation for luatex 1.21 (texlive 2025 pretest)

[David Carlisle]

The new luatex shows differences in the way it indents and abbreviates  log
error lines.

This is "only" logging but breaks several tests in the latex test suite
which is essentially a regression test based around diff-ing normalised
logs.

If the change is intentional we can update the reference results (and
maintainers of other packages using l3build tests will have to do similar)
but if this change might be reverted we will hold off updating the test
suite.

Attached is a small test file and the tl2024 and tl2025 log.

The diff is

$ diff 24.log 25.log
1c1
< This is LuaTeX, Version 1.18.0 (TeX Live 2024)  (format=luatex 2025.1.30)
 12 FEB 2025 19:16
---
> This is LuaTeX, Version 1.21.0 (TeX Live 2025)  (format=luatex 2025.2.12)
 12 FEB 2025 19:16
7c7
<                         x}
---
>                           x}
10c10
< l.5 ...elax\relax\relax\relax\relax\relax\show\relax
---
> l.5 ...ax\relax\relax\relax\relax\relax\show\relax
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