feat(Improvements): Migrate caching, base_dir, util, and symlink test to testify and improvements (#4828)

* feat(Improvements): Migrate caching, base_dir, util, and symlink tests to testify

* test: Clean up imports and fix context leak in Batch 6

* test: Address PR feedback (defer Close in util_test, use UTC for clocks)

* fix: ignore errors in defer calls in util_test to satisfy errcheck

* fix: restore file.Close() assertions inside defer blocks

* fix: resolve Test_getObjectPath bug and use idiomatic assertions

Author: charith87