auditbeat: kprobes remain inserted after process termination

[efd6]

For confirmed bugs, please report:

• Version: originally identified on 5186feb35defc05a5c0de7fcfa96df970913a070 but confirmed on latest master d00c2fe38b16603a32ef831c05c73de1c31929ed.
• Operating System: linux
• Steps to Reproduce:
  1. Checkout and build x-pack auditbeat.
  2. Using the default configuration run ./auditbeat run -d '*' -e until it has gone through the set up process and is reporting events.
  3. Cancel the process with ^C.
  4. List installed probes.

     # perf probe --list
       auditbeat_22327:inet_csk_accept_ret (on inet_csk_accept%return with sock laddr lport raddr rport famil
       auditbeat_22327:sys_execve_ret (on __x64_sys_execve%return with retval)
       auditbeat_22327:tcp4_connect_out (on tcp_v4_connect%return with retval)
       auditbeat_22327:tcp6_connect_out (on tcp_v6_connect%return with retval)

This is not the complete set of probes that are installed, so it seems that just these are missed during unload.

Found during exploration of #17165.

/cc @adriansr

[elasticmachine]

Pinging @elastic/security-external-integrations (Team:Security-External Integrations)