enhance: clean filepath in mountpoint

[Ace-Tang]

Ⅰ. Describe what this PR did

clean filepath in mountpoint source and destination, replace "/.." by "/" at the beginning of a path,
remove last "/" if exist.

Ⅱ. Does this pull request fix one issue?

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

Ⅴ. Special notes for reviews

[rudyfly]

LGTM

[Ace-Tang]

CRI test always fail cause of network.

[codecov-io]

Codecov Report

Merging #2157 into master will increase coverage by 0.04%.
The diff coverage is 100%.

@@            Coverage Diff            @@
##           master   #2157      +/-   ##
=========================================
+ Coverage   64.36%   64.4%   +0.04%     
=========================================
  Files         209     209              
  Lines       16664   16669       +5     
=========================================
+ Hits        10725   10736      +11     
+ Misses       4608    4602       -6     
  Partials     1331    1331

Flag	Coverage Δ
#criv1alpha1test	32.97% <83.33%> (+0.08%)	⬆️
#criv1alpha2test	33.36% <83.33%> (+0.01%)	⬆️
#integrationtest	39.26% <100%> (ø)	⬆️
#unittest	23.85% <0%> (-0.01%)	⬇️

Impacted Files	Coverage Δ
daemon/mgr/container_storage.go	50% <100%> (+0.47%)	⬆️
apis/opts/mountpoint.go	90.14% <100%> (+0.14%)	⬆️
daemon/logger/jsonfile/utils.go	71.54% <0%> (-1.63%)	⬇️
daemon/mgr/container.go	56.51% <0%> (-0.21%)	⬇️
cri/stream/runtime.go	70.58% <0%> (+2.35%)	⬆️
cri/stream/portforward/httpstream.go	75.83% <0%> (+6.66%)	⬆️