Leaked termini and qdr_link_t at router shutdown

[ganeshmurthy]

When a attach comes in just before router shutdown, the qdr_link_first_attach() is called which adds an action to the core thread with the qdr_link_inbound_first_attach_CT callback. When discard is true, qdr_link_inbound_first_attach_CT does not free the termini. It cannot free the qdr_link_t object since someone is holding its reference and that person might try to use it.
This leak can be reproduced intermittently by running the system_tests_http2_tls.py system test.

56: ERROR: Aborted due to unexpected alloc pool leak of type 'qdr_link_t'
56: 
56: <<<<
56: 
56: Router QDR debug dump file:
56: >>>>
56: alloc.c: Items of type 'qd_iterator_t' remain allocated at shutdown: 1 (SUPPRESSED)
56: alloc.c: Items of type 'qdr_field_t' remain allocated at shutdown: 1 (SUPPRESSED)
56: alloc.c: Items of type 'qd_buffer_t' remain allocated at shutdown: 1 (SUPPRESSED)
56: alloc.c: Items of type 'qdr_terminus_t' remain allocated at shutdown: 2
56: Leak: 2022-04-06 13:48:04.996099 +0000 type: qdr_terminus_t address: 0x612000035f50
56: /lib64/libasan.so.6(+0x44701) [0x7fba53ea6701]
56: skrouterd(qd_alloc+0x1fe) [0x4c064e]
56: skrouterd(qdr_terminus+0x2e) [0x6226ae]
56: skrouterd() [0x6c6f67]
56: skrouterd() [0x6d27f2]
56: skrouterd() [0x67aa85]
56: skrouterd() [0x682156]
56: /lib64/libc.so.6(+0x8db1a) [0x7fba528b4b1a]
56: /lib64/libc.so.6(+0x112660) [0x7fba5[2939](https://github.com/skupperproject/skupper-router/runs/5851875396?check_suite_focus=true#step:26:2939)660]
56: 
56: Leak: 2022-04-06 13:48:04.996123 +0000 type: qdr_terminus_t address: 0x612000035dd0
56: /lib64/libasan.so.6(+0x44701) [0x7fba53ea6701]
56: skrouterd(qd_alloc+0x1fe) [0x4c064e]
56: skrouterd(qdr_terminus+0x2e) [0x6226ae]
56: skrouterd() [0x6c7009]
56: skrouterd() [0x6d27f2]
56: skrouterd() [0x67aa85]
56: skrouterd() [0x682156]
56: /lib64/libc.so.6(+0x8db1a) [0x7fba528b4b1a]
56: /lib64/libc.so.6(+0x112660) [0x7fba52939660]
56: 
56: alloc.c: Items of type 'qdr_link_t' remain allocated at shutdown: 1
56: Leak: 2022-04-06 13:48:04.996134 +0000 type: qdr_link_t address: 0x617000085490
56: /lib64/libasan.so.6(+0x44701) [0x7fba53ea6701]
56: skrouterd(qd_alloc+0x1fe) [0x4c064e]
56: skrouterd(qdr_link_first_attach+0x42) [0x5a4332]
56: skrouterd() [0x6c7047]
56: skrouterd() [0x6d27f2]
56: skrouterd() [0x67aa85]
56: skrouterd() [0x682156]
56: /lib64/libc.so.6(+0x8db1a) [0x7fba528b4b1a]
56: /lib64/libc.so.6(+0x112660) [0x7fba52939660]
56: 
56: alloc.c: Items of type 'qd_http2_buffer_t' remain allocated at shutdown: 1 (SUPPRESSED)

https://github.com/skupperproject/skupper-router/runs/5851875396?check_suite_focus=true#step:26:2902

[ganeshmurthy]

Upon @kgiusti 's advice I will upload a partial fix for this issue. The fix will just free the termini objects and suppress the qdr_link_t leak