Call out to the shell less often in htpdate.service.

On my test system they all are run within the same seconds, but it adds up to
everything else we're doing at the same time.

Will-Fix: #10612

config/chroot_local-includes/lib/systemd/system/htpdate.service

@@ -10,10 +10,11 @@ Environment=DONE_FILE=/run/htpdate/done
 Environment=SUCCESS_FILE=/run/htpdate/success
 Environment=LOG=/var/log/htpdate.log
 EnvironmentFile=/etc/default/htpdate.*
-ExecStartPre=/bin/sh -c '[ -n "${HTTP_USER_AGENT}"  ]'
-ExecStartPre=/bin/sh -c '[ -n "${HTP_POOL_PAL}"     ]'
-ExecStartPre=/bin/sh -c '[ -n "${HTP_POOL_NEUTRAL}" ]'
-ExecStartPre=/bin/sh -c '[ -n "${HTP_POOL_FOE}"     ]'
+ExecStartPre=/bin/sh -c \
+    '[ -n "${HTTP_USER_AGENT}"  ] && \
+     [ -n "${HTP_POOL_PAL}"     ] && \
+     [ -n "${HTP_POOL_NEUTRAL}" ] && \
+     [ -n "${HTP_POOL_FOE}"     ]'
 ExecStartPre=/bin/rm -f "${DONE_FILE}"
 ExecStartPre=/bin/rm -f "${SUCCESS_FILE}"
 ExecStartPre=/usr/bin/install -o root -g root -m 0755 -d /run/htpdate