rules: use execute_after_dh_auto_install

this avoids calling dh_auto_install manually again

also, this fixes the override: we need to fix the installed files in any
type of build, not only during arch-builds

debian/rules

@@ -71,9 +71,7 @@ override_dh_auto_configure:
 		$(extra_cmake_args)
 
 
-override_dh_auto_install-arch:
-	dh_auto_install
-
+execute_after_dh_auto_install:
 	# Policy § 10.4. Remove this if https://bugs.debian.org/904409 gets fixed.
 	sed -i 's,bin/env perl,bin/perl,' debian/tmp/usr/lib/$(DEB_HOST_MULTIARCH)/qt6/libexec/*.pl \
 		debian/tmp/usr/lib/$(DEB_HOST_MULTIARCH)/qt6/mkspecs/features/data/unix/findclasslist.pl