Support checking out msft repo. (sonic-net#103)

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### Description of PR
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- Please include a summary of the change and which issue is fixed.
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To enable PR testing in the msft repo, we need to ensure support for checking out its code. This PR introduces the way to enable code checkout for the msft repo.

Summary:
Fixes # (issue)

### Type of change

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- Fill x for your type of change.
- e.g.
- [x] Bug fix
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- [ ] Bug fix
- [ ] Testbed and Framework(new/improvement)
- [ ] New Test case
 - [ ] Skipped for non-supported platforms
- [ ] Test case improvement

### Back port request
- [ ] 202012
- [ ] 202205
- [ ] 202305
- [ ] 202311
- [ ] 202405
- [ ] 202411

### Approach
#### What is the motivation for this PR?
To enable PR testing in the msft repo, we need to ensure support for checking out its code. This PR introduces the way to enable code checkout for the msft repo.

#### How did you do it?
If repo_name contains msft, we will check out msft test repo.

#### How did you verify/test it?
Test by pipeline.

#### Any platform specific information?

#### Supported testbed topology if it's a new test case?

### Documentation
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(If it's a new feature, new test case)
Did you update documentation/Wiki relevant to your implementation?
Link to the wiki page?
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Author: mssonicbld

.azure-pipelines/test_plan.py

@@ -27,7 +27,9 @@
 BUILDIMAGE_REPO_FLAG = "buildimage"
 MGMT_REPO_FLAG = "sonic-mgmt"
 INTERNAL_REPO_LIST = ["Networking-acs-buildimage", "sonic-mgmt-int"]
+MSFT_REPO_FLAG = "msft"
 GITHUB_SONIC_MGMT_REPO = "https://github.com/sonic-net/sonic-mgmt"
+GITHUB_SONIC_MGMT_REPO_MSFT = "https://github.com/Azure/sonic-mgmt.msft"
 INTERNAL_SONIC_MGMT_REPO = "https://dev.azure.com/mssonic/internal/_git/sonic-mgmt-int"
 PR_TEST_SCRIPTS_FILE = "pr_test_scripts.yaml"
 SPECIFIC_PARAM_KEYWORD = "specific_param"
@@ -276,7 +278,11 @@ def create(self, topology, test_plan_name="my_test_plan", deploy_mg_extra_params
 
         # If triggered by the internal repos, use internal sonic-mgmt repo as the code base
         sonic_mgmt_repo_url = GITHUB_SONIC_MGMT_REPO
-        if kwargs.get("source_repo") in INTERNAL_REPO_LIST:
+
+        if MSFT_REPO_FLAG in repo_name:
+            sonic_mgmt_repo_url = GITHUB_SONIC_MGMT_REPO_MSFT
+
+        elif kwargs.get("source_repo") in INTERNAL_REPO_LIST:
             sonic_mgmt_repo_url = INTERNAL_SONIC_MGMT_REPO
 
         # If triggered by mgmt repo, use pull request id as the code base