test(SYSTEMD): make the man command succeed

Document the reason of the existing workaround.

Move the existing logic to the initramfs.testing generation phase
and make the steps more generic.

This change makes the test pass on debian.

Author: LaszloGombos

test/TEST-02-SYSTEMD/systemd-analyze.sh

@@ -1,7 +1,5 @@
 #!/bin/bash
 
-cp /usr/bin/true /usr/bin/man
-
 for i in \
     sysinit.target \
     basic.target \

test/TEST-02-SYSTEMD/test.sh

@@ -102,9 +102,15 @@ test_setup() {
         export initdir=$TESTDIR/overlay
         # shellcheck disable=SC1090
         . "$basedir"/dracut-init.sh
-        inst_multiple poweroff shutdown dd
+        inst_multiple poweroff shutdown dd true
+
         inst_hook shutdown-emergency 000 ./hard-off.sh
+
+        # systemd-analyze.sh calls man indirectly
+        # make the man command succeed always
+        inst "$(find_binary true)" "/usr/bin/man"
         inst_hook pre-pivot 000 ./systemd-analyze.sh
+
         inst_hook emergency 000 ./hard-off.sh
     )
     "$basedir"/dracut.sh -l -i "$TESTDIR"/overlay / \