test(e2e/v2): add test cases for dfcache

[gaius-qi]

Description

This pull request introduces a new function to calculate the SHA-256 checksum for a task by accessing a persistent cache. The most important change is the addition of the new function CalculateSha256ByPersistentCacheTaskID.

New functionality:

• test/e2e/v2/util/task.go: Added CalculateSha256ByPersistentCacheTaskID function to calculate the SHA-256 checksum for a task by accessing a persistent cache path. This function iterates over the provided pods, checks if the content path exists, and computes the SHA-256 checksum if the path is found.

Related Issue

Motivation and Context

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation Update (if none of the other choices apply)

Checklist

• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 35.83%. Comparing base (3973340) to head (1ef15f6).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##           main    #3833       +/-   ##
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+ Coverage      0   35.83%   +35.83%     
=========================================
  Files         0      337      +337     
  Lines         0    38991    +38991     
=========================================
+ Hits          0    13973    +13973     
- Misses        0    24098    +24098     
- Partials      0      920      +920     

Flag	Coverage Δ
unittests	35.83% <ø> (?)

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see 337 files with indirect coverage changes

[chlins]

lgtm