[java-debug] remove '@theia/java-debug' ext

Removes the `@theia/java-debug` extension since it is
contributed by a builtin extension, and will no longer be
maintained by the project. The extension remains in the Git
history for anyone who would like to reference it or maintain
it.

Signed-off-by: Vincent Fugnitto <vincent.fugnitto@ericsson.com>

.travis.yml

@@ -28,7 +28,6 @@ cache:
   - packages/filesystem/node_modules
   - packages/getting-started/node_modules
   - packages/git/node_modules
-  - packages/java-debug/node_modules
   - packages/java/node_modules
   - packages/json/node_modules
   - packages/keymaps/node_modules
@@ -63,7 +62,6 @@ cache:
   - packages/variable-resolver/node_modules
   - packages/workspace/node_modules
 # end_cache_directories
-  - packages/java-debug/download
 before_cache:
   # Runs before the cache is updated, after successful CI
   - rm -f node_modules/@theia/electron/post-install.log