add msuseragent policy to short codes (Azure#26469)

### Packages impacted by this PR


### Issues associated with this PR


### Describe the problem that is addressed by this PR


### What are the possible designs available to address the problem? If
there are more than one possible design, why was the one in this PR
chosen?


### Are there test cases added in this PR? _(If not, why?)_


### Provide a list of related PRs _(if any)_


### Command used to generate this PR:**_(Applicable only to SDK release
request PRs)_

### Checklists
- [ ] Added impacted package name to the issue description
- [ ] Does this PR needs any fixes in the SDK Generator?** _(If so,
create an Issue in the
[Autorest/typescript](https://github.com/Azure/autorest.typescript)
repository and link it here)_
- [ ] Added a changelog (if necessary)

Author: rtrevino89

sdk/communication/communication-short-codes/karma.conf.js

@@ -53,6 +53,7 @@ module.exports = function (config) {
       "AZURE_TENANT_ID",
       "COMMUNICATION_SKIP_INT_PHONENUMBERS_TESTS",
       "RECORDINGS_RELATIVE_PATH",
+      "AZURE_USERAGENT_OVERRIDE",
     ],
 
     // test results reporter to use