Remove  as they made real HTTP calls to quay.io registry endpoints which violates unit testing principles.

Problem

TestGetDigest and TestGetManifest from imagemetadata_test.go havethe following issues:

• Required internet access to pass
• Used hardcoded digests that could break if images are updated
• Tested integration with external services (belongs in e2e tests)
• Verified global cache state which is implementation detail

Solution

The pure logic being tested is already covered by existing unit tests:

• TestGetRegistryOverrides (registry override logic)
• TestSeekOverride (mirror seeking)
• TestTryOnlyNamespaceOverride,
• TestTryExactCoincidenceOverride,
• TestTryOnlyRootRegistryOverride (override matching)
• TestMirrorAvailabilityCache, TestCacheCleanupOnExpiration (caching)