Fix the error message for auth token not found.

This CL fixes the error message returned when an auth token is not
found for IC.

Bug: 198731997
Test: N/A

Change-Id: I4512c89f7793f2c50a61d221abe20bdfa5e87102
diff --git a/keystore2/src/enforcements.rs b/keystore2/src/enforcements.rs
index e9a58f9..997e739 100644
--- a/keystore2/src/enforcements.rs
+++ b/keystore2/src/enforcements.rs
@@ -837,8 +837,12 @@
                         .context("In get_auth_tokens: No auth token found.");
                 }
             } else {
-                return Err(AuthzError::Rc(AuthzResponseCode::NO_AUTH_TOKEN_FOUND))
-                    .context("In get_auth_tokens: Passed-in auth token max age is zero.");
+                return Err(AuthzError::Rc(AuthzResponseCode::NO_AUTH_TOKEN_FOUND)).context(
+                    concat!(
+                        "In get_auth_tokens: No auth token found for ",
+                        "the given challenge and passed-in auth token max age is zero."
+                    ),
+                );
             }
         };
         // Wait and obtain the timestamp token from secure clock service.