[gdb/testsuite] Fix breakpoint regexp in gdb.ada/out_of_line_in_inlined.exp

With a gdb 13.2 based package on openSUSE Tumbleweed i586, I ran into:
...
(gdb) run ^M
Starting program: out_of_line_in_inlined/foo_o224_021-all ^M
[Thread debugging using libthread_db enabled]^M
Using host libthread_db library "/lib/libthread_db.so.1".^M
^M
Breakpoint 1.1, foo_o224_021.child1.child2 (s=...) at foo_o224_021.adb:26^M
26                  for C of S loop^M
(gdb) FAIL: gdb.ada/out_of_line_in_inlined.exp: scenario=all: \
  run to foo_o224_021.child1.child2
...

I can reproduce the same issue with gdb trunk on x86_64, by using optimize=-O3
instead of optimize=-O2.

Fix this by using $bkptno_num_re.

Tested on x86_64-linux.

PR testsuite/30539
Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30539