functional: add disk io failure case

[tangcong]

This PR does the following things:

• fixes a serious bug for the FAILPOINTS case.
• add functional test case for PR etcdserver: ignore old leader's request to revoke lease #12531. FAILPOINTS and short ttl lease case are very flaky, In order to improve the stability of the test cases, I implemented a new case and checker based on the functional extension mechanism, which can be specified through the configuration file.

 cases:
  - FAILPOINTS_WITH_DISK_IO_LATENCY
   
 failpoint-commands:
  - sleep(3000)

  stressers:
  - type: LEASE
    weight: 0.1

  checkers:
  - SHORT_TTL_LEASE_EXPIRE

[codecov-commenter]

Codecov Report

Merging #12898 (4fb2209) into master (cc52d99) will decrease coverage by 3.83%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #12898      +/-   ##
==========================================
- Coverage   72.34%   68.51%   -3.83%     
==========================================
  Files         428      408      -20     
  Lines       33888    32799    -1089     
==========================================
- Hits        24515    22471    -2044     
- Misses       7413     8342     +929     
- Partials     1960     1986      +26     

Flag	Coverage Δ
all	68.51% <ø> (-3.83%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
raft/quorum/quorum.go	0.00% <0.00%> (-100.00%)	⬇️
raft/tracker/state.go	0.00% <0.00%> (-100.00%)	⬇️
...ver/proxy/grpcproxy/adapter/lock_client_adapter.go	0.00% <0.00%> (-100.00%)	⬇️
pkg/report/report.go	0.00% <0.00%> (-95.58%)	⬇️
pkg/report/timeseries.go	0.00% <0.00%> (-86.77%)	⬇️
pkg/osutil/interrupt_unix.go	0.00% <0.00%> (-82.61%)	⬇️
pkg/osutil/osutil.go	0.00% <0.00%> (-75.00%)	⬇️
pkg/report/weighted.go	0.00% <0.00%> (-69.77%)	⬇️
client/v3/namespace/lease.go	0.00% <0.00%> (-69.24%)	⬇️
server/proxy/grpcproxy/election.go	6.25% <0.00%> (-68.75%)	⬇️
... and 99 more

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[gyuho]

lgtm, awesome thanks!

[tangcong]

thanks @gyuho