Ci doc build backport 2.9

[hdiethelm]

Backport of #4150 to 2.9

Feel free to merge if useful or drop if not needed, took me just a few minutes.

I left the commits as they where, I hope there is not to much trouble merging 2.9 to master.

Edit: I also added @grandixximo's commit that cancels outdated CI run's for PR's

[hdiethelm]

Hmm. github is again sleepy today. Let's see how it looks tomorrow.

[grandixximo]

Took almost 4 hours but it passed, @hdiethelm ready to merge?

I cancelled the stuck CI build manually.

[hdiethelm]

Took almost 4 hours but it passed, @hdiethelm ready to merge?

I cancelled the stuck CI build manually.

Yes,i just wanted to check if the contents of the tar look correct.

BTW:
It looks like the german translations are broken, but probably not caused by this PR, the contents of the tar look good, same issue if I open the html/de/index.html when built locally. It might work on the server but it also might not.

It might be good to investigate before uploading this artifact to the homepage server.

[grandixximo]

You were lucky, because today sid is broken altogether...
I will try to have a clean worktree with 2.9 see why german is broken

[hdiethelm]

I added the sid allow fail in this PR, so all fine anyway... ;-) Thanks!

[grandixximo]

I looked into the broken German index. It is not caused by this PR, but here is a fix if useful.

html/de/index.html references index.css, linuxcnc-logo-chips.png, plus.png and minus.png with bare relative paths, but those assets only exist in the html/ root next to the English index. They are never copied into html/de/, so the German index loads with no stylesheet, a broken logo and broken expand/collapse icons. The chapter pages are fine because asciidoc sets stylesdir for them; only the hand-written index escapes that.

The per-language index rule just needs to copy those four assets into each html/<lang>/ dir:

diff --git a/docs/src/Submakefile b/docs/src/Submakefile
@@ -518,6 +518,8 @@ $(DOC_DIR)/html/%/index.html: $(DOC_SRCDIR)/index_%.tmpl ../VERSION $(DOC_SRCDIR
 	cat $(filter-out ../VERSION, $^) | \
 		sed "s/@VERSION@/`cat ../VERSION`/" | \
 		if [ "yes" != "$(BUILD_DOCS_TRANSLATED)" ]; then sed '/@TRANSLATIONS@/,/@ENDTRANSLATIONS@/d' ; else grep -Ev '@(END)?TRANSLATIONS@'; fi > $@
+	cp -f $(DOC_DIR)/html/index.css $(DOC_DIR)/html/linuxcnc-logo-chips.png \
+		$(DOC_DIR)/html/plus.png $(DOC_DIR)/html/minus.png $(dir $@)
 
 $(DOC_DIR)/html/index.html: $(DOC_SRCDIR)/index.tmpl objects/index.incl $(DOC_SRCDIR)/index.foot ../VERSION $(DOC_SRCDIR)/Submakefile

Tested with a full build-doc.sh: the German index now renders styled, and verify-clean-repo stays clean.