[Fix] RAFT KITTI test cfg and set_env

[MeowZheng]

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Motivation

1. Image norm arguments in kitti2015_raft_test.py don't suit raft.
2. set_env supports model testing

Modification

1. configs/base/datasets/kitti2015_raft_test.py
2. mmflow/utils/set_env.py

BC-breaking (Optional)

Does the modification introduce changes that break the backward-compatibility of the downstream repositories?
If so, please describe how it breaks the compatibility and how the downstream projects should modify their code to keep compatibility with this PR.

Use cases (Optional)

If this PR introduces a new feature, it is better to list some use cases here, and update the documentation.

Checklist

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, like MMDet or MMCls.
• CLA has been signed and all committers have signed the CLA in this PR.

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.56%. Comparing base (cf1c2f2) to head (ae6b61a).
⚠️ Report is 13 commits behind head on master.

Files with missing lines	Patch %	Lines
mmflow/utils/set_env.py	33.33%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #165      +/-   ##
==========================================
- Coverage   69.03%   68.56%   -0.48%     
==========================================
  Files          92       92              
  Lines        5148     5153       +5     
  Branches      733      735       +2     
==========================================
- Hits         3554     3533      -21     
- Misses       1481     1505      +24     
- Partials      113      115       +2     

Flag	Coverage Δ
unittests	68.56% <33.33%> (-0.44%)	⬇️

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