handle azure Gen2 storage path when parsing ref

[SVilgelm]

Summary

• Cherry-picks the ABFS Gen2 path-parsing fix from the legacy flytestdlib repo (original PR: https://github.com/flyteorg/flytestdlib/pull/841) onto main.
• Fixes DataReference.Split for Azure ADLS Gen2 (abfs://container@account.dfs.core.windows.net/path) URLs, where url.Parse puts the container in the User field instead of Host.
• Scopes the u.User.Username() override to abfs/abfss so s3://accessKey:secret@bucket/key-style URLs still return bucket as the container.
• Adds a regression test for the S3-with-userinfo case and an abfss test.

Test plan

• go test ./flytestdlib/storage/... -run TestDataReference

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR updates flytestdlib/storage to correctly split Azure ADLS Gen2 (ABFS) URLs where net/url.Parse places the filesystem/container name in URL.User due to the container@host authority format.

Changes:

• Update DataReference.Split() to use u.User.Username() as the container when present (to support abfs://container@account.dfs.core.windows.net/...).
• Expand TestDataReference_Split with ABFS (with/without path) and GCS subtests.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
flytestdlib/storage/storage.go	Adjusts DataReference.Split() to extract the container from URL.User when @ is present in the authority (ABFS Gen2 format).
flytestdlib/storage/storage_test.go	Adds subtests covering ABFS Gen2 parsing and adds additional scheme coverage (GCS).

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