[tsp-client convert] ARM converter adds @useAuth to main.tsp

[darkoa-msft]

Before filling a bug

• have you checked the faq for known issues.
• have you checked existing issues

tsp-client convert --arm adds @useAuth(AadOauth2Auth<["user_impersonation"]>) to main.tsp, which causes the wrong security definition to be created in ARM swagger.

Expected behavior
After conversion, running tsp compile should produce the standard security definition.

Additional context
To repro, take an existing swagger, convert it and check main.tsp