bgpd: fix crash at no rpki (backport 9.1 and lower) (backport #16612)

[mergify]

When 'no rpki' is requested and the rtrlib RPKI object was freed, bgpd is crashing.

RPKI is configured in VRF red.

ip l set red down
ip l del red
printf 'conf\n vrf red\n no rpki' | vtysh

Core was generated by `/usr/bin/bgpd -A 127.0.0.1 -M snmp -M rpki -M bmp'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0 __pthread_kill_implementation (no_tid=0, signo=11, threadid=140411103615424) at ./nptl/pthread_kill.c:44
44 ./nptl/pthread_kill.c: No such file or directory.
[Current thread is 1 (Thread 0x7fb401f419c0 (LWP 190226))]
(gdb) bt
#0 __pthread_kill_implementation (no_tid=0, signo=11, threadid=140411103615424) at ./nptl/pthread_kill.c:44
#1 __pthread_kill_internal (signo=11, threadid=140411103615424) at ./nptl/pthread_kill.c:78
#2 __GI___pthread_kill (threadid=140411103615424, signo=signo@entry=11) at ./nptl/pthread_kill.c:89
#3 0x00007fb4021ad476 in __GI_raise (sig=11) at ../sysdeps/posix/raise.c:26
#4 0x00007fb4025ce22b in core_handler (signo=11, siginfo=0x7fff831b2d70, context=0x7fff831b2c40) at lib/sigevent.c:248
#5
#6 rtr_mgr_remove_group (config=0x55fe8789f750, preference=11) at /build/make-pkg/output/source/DIST_RTRLIB/rtrlib/rtrlib/rtr_mgr.c:607
#7 0x00007fb40145f518 in rpki_delete_all_cache_nodes (rpki_vrf=0x55fe8789f4f0) at bgpd/bgp_rpki.c:442
#8 0x00007fb401463098 in no_rpki_magic (self=0x7fb40146bba0 <no_rpki_cmd>, vty=0x55fe877f5130, argc=2, argv=0x55fe877fccd0) at bgpd/bgp_rpki.c:1732
#9 0x00007fb40145c09a in no_rpki (self=0x7fb40146bba0 <no_rpki_cmd>, vty=0x55fe877f5130, argc=2, argv=0x55fe877fccd0) at ./bgpd/bgp_rpki_clippy.c:37
#10 0x00007fb402527abc in cmd_execute_command_real (vline=0x55fe877fd150, vty=0x55fe877f5130, cmd=0x0, up_level=0) at lib/command.c:984
#11 0x00007fb402527c35 in cmd_execute_command (vline=0x55fe877fd150, vty=0x55fe877f5130, cmd=0x0, vtysh=0) at lib/command.c:1043
#12 0x00007fb4025281e5 in cmd_execute (vty=0x55fe877f5130, cmd=0x55fe877fb8c0 "no rpki\n", matched=0x0, vtysh=0) at lib/command.c:1209
#13 0x00007fb4025f0aed in vty_command (vty=0x55fe877f5130, buf=0x55fe877fb8c0 "no rpki\n") at lib/vty.c:615
#14 0x00007fb4025f2a11 in vty_execute (vty=0x55fe877f5130) at lib/vty.c:1378
#15 0x00007fb4025f513d in vtysh_read (thread=0x7fff831b5fa0) at lib/vty.c:2373
#16 0x00007fb4025e9611 in event_call (thread=0x7fff831b5fa0) at lib/event.c:2011
#17 0x00007fb402566976 in frr_run (master=0x55fe871a14a0) at lib/libfrr.c:1212
#18 0x000055fe857829fa in main (argc=9, argv=0x7fff831b6218) at bgpd/bgp_main.c:549

Fixes: 8156765 ("bgpd: Add no rpki command")

(cherry picked from commit 4e053d6)

There is also an issue when doing "rpki reset" and then "no rpki".

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This is an automatic backport of pull request #16612 done by Mergify.