test: add unit tests for convertUint32ToIntSlice, rmMultipleDirs and mapMountFlag

[Shreya2005-2005]

Description

Adds unit tests for three helper functions that had no test coverage:

• convertUint32ToIntSlice in pkg/unikontainers/utils.go: converts a
  []uint32 to []int
• rmMultipleDirs in pkg/unikontainers/utils.go: removes multiple
  directories under a given prefix path
• mapMountFlag in pkg/unikontainers/mount.go: maps a mount option
  string to its corresponding flag struct

Related issues

• Fixes Add more unit tests #96

How was this tested?

Ran unit tests locally:
go test ./pkg/unikontainers/... -v -run "TestConvertUint32ToIntSlice|TestRmMultipleDirs|TestMapMountFlag"
All test cases passed. Full package tests also pass:
go test ./pkg/... ./internal/...
Linter passes locally (make lint, 0 issues).

LLM usage

Claude Sonnet 4.6 was used to assist in understanding the codebase
and test structure. All code was reviewed and understood before submission.

Checklist

• I have read the contribution guide.
• The linter passes locally (make lint).
• The e2e tests of at least one tool pass locally.
• If LLMs were used: I have read the llm policy.

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[cmainas]

Hello @Shreya2005-2005 ,

thank you for the PR. However, I am not sure if we should test such small and straightforward functions as unit tests.