Revert ".travis.yml: Cache Avocado cache"

This reverts commit c1073e44b46490133e16420e1784dec7bcd4e030.

The Avocado tests have been removed from Travis a long time ago with
commit c5008c76ee ("gitlab: add acceptance testing to system builds"),
so we don't need to cache the avocado files here anymore.

Message-ID: <20240320104144.823425-4-thuth@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
diff --git a/.travis.yml b/.travis.yml
index 8a3ae76..8da88c4 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,8 +12,6 @@
   timeout: 1200
   ccache: true
   pip: true
-  directories:
-  - $HOME/avocado/data/cache
 
 
 # The channel name "irc.oftc.net#qemu" is encrypted against qemu/qemu