trace: Move LTTng specific declartion to .inc file

LTTng tracepoint probe declaration is not really following a C standard that
coccinelle and checkSpace.pl likes.

Move everything to a .inc file and standardize the trace_probes_circuit.h
header to include that LTTng specific file if the instrumentation was enabled
at configure time.

Part of #32910

Signed-off-by: David Goulet <dgoulet@torproject.org>