test: disable pipefail again in monitor_check_rr()

test: disable pipefail again in monitor_check_rr()

Partially reverts d6b379370485b9651f86b628ce980de719299eb4.

On Ubuntu 26.04 devel, TEST-75-RESOLVED often fails at this stage,
despite the matching query apparently being found:

 + monitor_check_rr '2025-12-18 16:02:54' 'follow10.so.close.signed.test IN CNAME follow11.yet.so.far.signed.test'
  + set +x
  Dec 18 16:02:54 ns1.unsigned.test resolvectl[552]: ← A: follow10.so.close.signed.test IN CNAME follow11.yet.so.far.signed.test
 + monitor_check_rr '2025-12-18 16:02:54' 'follow11.yet.so.far.signed.test IN CNAME follow12.getting.hot.signed.test'
  + set +x
  Dec 18 16:02:54 ns1.unsigned.test resolvectl[552]: ← A: follow11.yet.so.far.signed.test IN CNAME follow12.getting.hot.signed.test
 + monitor_check_rr '2025-12-18 16:02:54' 'follow12.getting.hot.signed.test IN CNAME follow13.almost.final.signed.test'
  + set +x
  Dec 18 16:02:54 ns1.unsigned.test resolvectl[552]: ← A: follow12.getting.hot.signed.test IN CNAME follow13.almost.final.signed.test
 + monitor_check_rr '2025-12-18 16:02:54' 'follow13.almost.final.signed.test IN CNAME follow14.final.signed.test'
  + set +x
  Dec 18 16:02:54 ns1.unsigned.test resolvectl[552]: ← A: follow13.almost.final.signed.test IN CNAME follow14.final.signed.test

Unsetting pipefail, as was done before d6b3793704, appears to fix the
problem.

(cherry picked from commit 7c9c34514a705ea0ce61432503a05162d0f658b0)
(cherry picked from commit ce35956b3a0bb88f65c9594cb224261804188439)
(cherry picked from commit f9e498483f277ccde0af141c60dc7c40f274a04b)