rtla/timerlat: Test BPF mode

rtla/timerlat: Test BPF mode

Using the RTLA_NO_BPF environmental variable, execute rtla-timerlat
tests both with and without BPF support to cover both paths.

If rtla is built without BPF or the osnoise:timerlat_sample trace event
is not available, test only the non-BPF path.

Cc: John Kacur <jkacur@redhat.com>
Cc: Luis Goncalves <lgoncalv@redhat.com>
Cc: Gabriele Monaco <gmonaco@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Link: https://lore.kernel.org/20250218145859.27762-9-tglozar@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>