fix: exec config leak in cri exec

[zhuangqh]

mark execConfig as exited and used when start exec fails
exec gc will collect this config

Signed-off-by: zhuangqh zhuangqhc@gmail.com

Ⅰ. Describe what this PR did

Ⅱ. Does this pull request fix one issue?

exec config object would leak in memory after CRI ExecSync

Ⅲ. Why don't you add test cases (unit test/integration test)? (你真的觉得不需要加测试吗？)

Ⅳ. Describe how to verify it

1. crictl exec into a container
2. inspect container and execconfig will be empty after several minutes.

Ⅴ. Special notes for reviews

[codecov]

Codecov Report

Merging #3000 into master will increase coverage by 0.62%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #3000      +/-   ##
==========================================
+ Coverage   67.41%   68.03%   +0.62%     
==========================================
  Files         291      291              
  Lines       18660    18663       +3     
==========================================
+ Hits        12579    12697     +118     
+ Misses       4572     4484      -88     
+ Partials     1509     1482      -27

Flag	Coverage Δ
#criv1alpha2_test	34.44% <11.11%> (-0.22%)	⬇️
#integration_test_0	36.4% <11.11%> (-0.01%)	⬇️
#integration_test_1	35.48% <100%> (+0.02%)	⬆️
#integration_test_2	36.37% <11.11%> (+0.01%)	⬆️
#integration_test_3	35.8% <11.11%> (?)
#node_e2e_test	34.01% <11.11%> (-0.21%)	⬇️
#unittest	26.68% <0%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
daemon/mgr/container_exec.go	80% <100%> (+0.42%)	⬆️
ctrd/watch.go	72.72% <0%> (-5.2%)	⬇️
ctrd/container.go	50.62% <0%> (-0.36%)	⬇️
apis/server/router.go	91.95% <0%> (+0.57%)	⬆️
daemon/mgr/spec_linux.go	79.26% <0%> (+1%)	⬆️
daemon/mgr/container_stats.go	71.66% <0%> (+1.11%)	⬆️
daemon/mgr/image.go	61.17% <0%> (+1.3%)	⬆️
ctrd/supervisord/daemon.go	49.12% <0%> (+1.31%)	⬆️
daemon/mgr/container_validation.go	40.09% <0%> (+1.8%)	⬆️
registry/auth.go	55.14% <0%> (+1.86%)	⬆️
... and 14 more

[fuweid]

LGTM