rtla: Use strdup() to simplify code

rtla: Use strdup() to simplify code

The actions_add_trace_output() and actions_add_shell() functions were
using calloc() followed by strcpy() to allocate and copy a string.
This can be simplified by using strdup(), which allocates memory and
copies the string in a single step.

Replace the calloc() and strcpy() calls with strdup(), making the
code more concise and readable.

Signed-off-by: Wander Lairson Costa <wander@redhat.com>
Link: https://lore.kernel.org/r/20260309195040.1019085-3-wander@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>