refactor: remove UserRealmURIPrefix from authority.Info

The field isn't used anywhere. Removing it simplifies the work on introducing
authority abstraction. We might re-add it once we need it for anything.

apps/internal/oauth/ops/authority/authority.go

@@ -344,7 +344,6 @@ type Info struct {
 	Host                      string
 	CanonicalAuthorityURI     string
 	AuthorityType             string
-	UserRealmURIPrefix        string
 	ValidateAuthority         bool
 	Tenant                    string
 	Region                    string
@@ -381,7 +380,6 @@ func NewInfoFromAuthorityURI(authority string, validateAuthority bool, instanceD
 		Host:                      u.Host,
 		CanonicalAuthorityURI:     fmt.Sprintf("https://%v/%v/", u.Host, tenant),
 		AuthorityType:             authorityType,
-		UserRealmURIPrefix:        fmt.Sprintf("https://%v/common/userrealm/", u.Hostname()),
 		ValidateAuthority:         validateAuthority,
 		Tenant:                    tenant,
 		InstanceDiscoveryDisabled: instanceDiscoveryDisabled,

apps/internal/oauth/ops/authority/authority_test.go

@@ -305,7 +305,6 @@ func TestCreateAuthorityInfoFromAuthorityUri(t *testing.T) {
 		Host:                  "login.microsoftonline.com",
 		CanonicalAuthorityURI: authorityURI,
 		AuthorityType:         "MSSTS",
-		UserRealmURIPrefix:    "https://login.microsoftonline.com/common/userrealm/",
 		Tenant:                "common",
 		ValidateAuthority:     true,
 	}