[Enhance] faster test

[okotaku]

Motivation

Faster test by using tiny-sd.

Checklist

Submitting this pull request means that,

Before PR:

• I have read and followed the workflow indicated in the CONTRIBUTING.md to create this PR.
• Pre-commit or linting tools indicated in CONTRIBUTING.md are used to fix the potential lint issues.
• Bug fixes are covered by unit tests, the case that causes the bug should be added in the unit tests.
• New functionalities are covered by complete unit tests. If not, please add more unit test to ensure the correctness.
• The documentation has been modified accordingly, including docstring or example tutorials.

After PR:

• If the modification has potential influence on downstream or other related projects, this PR should be tested with some of those projects.
• CLA has been signed and all committers have signed the CLA in this PR.

[codecov]

Codecov Report

Patch has no changes to coverable lines.

❗ Current head 5ba2180 differs from pull request most recent head 6e4ef2a. Consider uploading reports for the commit 6e4ef2a to get more accurate results

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[liuwenran]

Thanks for your contribution. We don't need to download sd15 weights any more when we runs ut. This pr will make our unit test faster.