teuthology/task: use grep switch instead of egrep

teuthology/task: use grep switch instead of egrep

Resolves:

    2025-11-30T03:49:48.951 DEBUG:teuthology.task.internal.syslog:Checking ubuntu@smithi155.front.sepia.ceph.com
    2025-11-30T03:49:48.952 DEBUG:teuthology.orchestra.run.smithi155:> egrep --binary-files=text '\bBUG\b|\bINFO\b|\bDEADLOCK\b' /home/ubuntu/cephtest/archive/syslog/kern.log | grep -v 'task .* blocked for more than .* seconds' | grep -v 'lockdep is turned off' | grep -v 'trying to register non-static key' | grep -v 'DEBUG: fsize' | grep -v CRON | grep -v 'BUG: bad unlock balance detected' | grep -v 'inconsistent lock state' | grep -v '*** DEADLOCK ***' | grep -v 'INFO: possible irq lock inversion dependency detected' | grep -v 'INFO: NMI handler (perf_event_nmi_handler) took too long to run' | grep -v 'INFO: recovery required on readonly' | grep -v 'ceph-create-keys: INFO' | grep -v INFO:ceph-create-keys | grep -v 'Loaded datasource DataSourceOpenStack' | grep -v 'container-storage-setup: INFO: Volume group backing root filesystem could not be determined' | egrep -v '\bsalt-master\b|\bsalt-minion\b|\bsalt-api\b' | grep -v ceph-crash | egrep -v '\btcmu-runner\b.*\bINFO\b' | head -n 1
    2025-11-30T03:49:48.983 INFO:teuthology.orchestra.run.smithi155.stderr:egrep: warning: egrep is obsolescent; using grep -E
    2025-11-30T03:49:48.983 INFO:teuthology.orchestra.run.smithi155.stderr:egrep: warning: egrep is obsolescent; using grep -E
    2025-11-30T03:49:48.983 INFO:teuthology.orchestra.run.smithi155.stderr:egrep: warning: egrep is obsolescent; using grep -E

Fixes: https://tracker.ceph.com/issues/74259
Signed-off-by: Patrick Donnelly <pdonnell@redhat.com>