Fix a test failure in test_hs_control_add_onion_helper_add_service().

This bug made the pipeline fail. It basically tries to access a service we just
freed because it's still on the service list.

It only occurs about once every 10 tests and it looks like this:

$ ./src/test/test hs_control/hs_control_add_onion_helper_add_service
hs_control/hs_control_add_onion_helper_add_service: [forking] =================================================================
==354311==ERROR: AddressSanitizer: heap-use-after-free on address 0x613000000940 at pc 0x55a159251b03 bp 0x7ffc6abb5b30 sp 0x7ffc6abb5b28
READ of size 8 at 0x613000000940 thread T0
^[[A
    #0 0x55a159251b02 in hs_service_ht_HT_FIND_P_ src/feature/hs/hs_service.c:153
    #1 0x55a159251b02 in hs_service_ht_HT_FIND src/feature/hs/hs_service.c:153
    #2 0x55a159251b02 in find_service src/feature/hs/hs_service.c:175
    #3 0x55a159251c2c in register_service src/feature/hs/hs_service.c:188
    #4 0x55a159262379 in hs_service_add_ephemeral src/feature/hs/hs_service.c:3811
    #5 0x55a158e865e6 in test_hs_control_add_onion_helper_add_service src/test/test_hs_control.c:847
    #6 0x55a1590fe77b in testcase_run_bare_ src/ext/tinytest.c:107
    #7 0x55a1590fee98 in testcase_run_forked_ src/ext/tinytest.c:201
    #8 0x55a1590fee98 in testcase_run_one src/ext/tinytest.c:267
    #9 0x55a1590ffb06 in tinytest_main src/ext/tinytest.c:454
    #10 0x55a158b1b1a4 in main src/test/testing_common.c:420
    #11 0x7f7f06f8dd09 in __libc_start_main ../csu/libc-start.c:308
    #12 0x55a158b21f69 in _start (/home/f/Computers/tor/mytor/src/test/test+0x372f69)

0x613000000940 is located 64 bytes inside of 344-byte region [0x613000000900,0x613000000a58)
freed by thread T0 here:
    #0 0x7f7f0774ab6f in __interceptor_free ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:123
    #1 0x55a158e86508 in test_hs_control_add_onion_helper_add_service src/test/test_hs_control.c:838
    #2 0x55a1590fe77b in testcase_run_bare_ src/ext/tinytest.c:107
    #3 0x55a1590fee98 in testcase_run_forked_ src/ext/tinytest.c:201
    #4 0x55a1590fee98 in testcase_run_one src/ext/tinytest.c:267
    #5 0x55a1590ffb06 in tinytest_main src/ext/tinytest.c:454
    #6 0x55a158b1b1a4 in main src/test/testing_common.c:420
    #7 0x7f7f06f8dd09 in __libc_start_main ../csu/libc-start.c:308

previously allocated by thread T0 here:
    #0 0x7f7f0774ae8f in __interceptor_malloc ../../../../src/libsanitizer/asan/asan_malloc_linux.cpp:145
    #1 0x55a15948b728 in tor_malloc_ src/lib/malloc/malloc.c:45
    #2 0x55a15948b7c0 in tor_malloc_zero_ src/lib/malloc/malloc.c:71
    #3 0x55a159261bb5 in hs_service_new src/feature/hs/hs_service.c:4290
    #4 0x55a159261f49 in hs_service_add_ephemeral src/feature/hs/hs_service.c:3758
    #5 0x55a158e8619f in test_hs_control_add_onion_helper_add_service src/test/test_hs_control.c:832
    #6 0x55a1590fe77b in testcase_run_bare_ src/ext/tinytest.c:107
    #7 0x55a1590fee98 in testcase_run_forked_ src/ext/tinytest.c:201
    #8 0x55a1590fee98 in testcase_run_one src/ext/tinytest.c:267
    #9 0x55a1590ffb06 in tinytest_main src/ext/tinytest.c:454
    #10 0x55a158b1b1a4 in main src/test/testing_common.c:420
    #11 0x7f7f06f8dd09 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: heap-use-after-free src/feature/hs/hs_service.c:153 in hs_service_ht_HT_FIND_P_
Shadow bytes around the buggy address:
  0x0c267fff80d0: 00 00 00 00 00 00 00 00 00 00 00 00 fa fa fa fa
  0x0c267fff80e0: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
  0x0c267fff80f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c267fff8100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c267fff8110: 00 00 00 00 00 00 00 00 fa fa fa fa fa fa fa fa
=>0x0c267fff8120: fd fd fd fd fd fd fd fd[fd]fd fd fd fd fd fd fd
  0x0c267fff8130: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x0c267fff8140: fd fd fd fd fd fd fd fd fd fd fd fa fa fa fa fa
  0x0c267fff8150: fa fa fa fa fa fa fa fa 00 00 00 00 00 00 00 00
  0x0c267fff8160: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0c267fff8170: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
  Shadow gap:              cc
==354311==ABORTING
[Lost connection!]
  [hs_control_add_onion_helper_add_service FAILED]
1/1 TESTS FAILED. (0 skipped)

src/test/test_hs_control.c

@@ -835,6 +835,7 @@ test_hs_control_add_onion_helper_add_service(void *arg)
   service_good = find_service(global_map, &pk_good);
   tt_int_op(smartlist_len(service_good->config.clients), OP_EQ, 1);
 
+  remove_service(global_map, service_good);
   hs_service_free(service_good);
 
   list_bad = smartlist_new();