{Core} Do not append/strip trailing slash in scope

[jiasli]

Description

Fix incorrect logic of resource_to_scopes and scopes_to_resource introduced by #15184.

According to Trailing slash and /.default,

• For some services, the trailing slash should not appear in the resource URI, like https://managedhsm.azure.com, and the corresponding scope should be https://managedhsm.azure.com/.default
• On the other hand, for some other services, the trailing slash is mandatory, like https://management.azure.com/, and the corresponding scope should be https://management.azure.com//.default - note the double slash!

This PR changes the behavior so that no extra logic is performed on the trailing slash - CLI only appends or strips /.default with no fancy logic.

[yonzhan]

Core

[arrownj]

👍