Updated logging extension to remove the period on ValidationFailed

_tokenValidationFailed format string includes the JWT token followed by a period, which if a dev troubleshooting copies incorrectly to the EOL will make the JWT invalid. 

Current: Failed to validate the token eyJhbGc.......HCwFmw.
Proposed: Failed to validate the token eyJhbGc.......HCwFmw

Author: muqeet-khan

src/Microsoft.AspNetCore.Authentication.JwtBearer/LoggingExtensions.cs

@@ -16,7 +16,7 @@ static LoggingExtensions()
             _tokenValidationFailed = LoggerMessage.Define<string>(
                 eventId: 1,
                 logLevel: LogLevel.Information,
-                formatString: "Failed to validate the token {Token}.");
+                formatString: "Failed to validate the token {Token}");
             _tokenValidationSucceeded = LoggerMessage.Define(
                 eventId: 2,
                 logLevel: LogLevel.Information,