Remove Travis CI status

Builds on travis-ci.org ceased on 2021-06-15.

README.md

 Code status:
 ------------
 
-* [![Travis CI status](https://secure.travis-ci.org/MariaDB/server.png?branch=10.2)](https://travis-ci.org/MariaDB/server) travis-ci.org (10.2 branch)
 * [![Appveyor CI status](https://ci.appveyor.com/api/projects/status/4u6pexmtpuf8jq66?svg=true)](https://ci.appveyor.com/project/rasmushoj/server) ci.appveyor.com
 
 ## MariaDB: drop-in replacement for MySQL
@@ -76,10 +75,3 @@ https://bugs.mysql.com
 
 The code for MariaDB, including all revision history, can be found at:
 https://github.com/MariaDB/server
-
-***************************************************************************
-
-Code status:
-------------
-
-* [![tests status](https://secure.travis-ci.org/MariaDB/server.png?branch=10.2)](https://travis-ci.org/MariaDB/server) travis-ci.org (10.2 branch)