Remove protoc installation from watchtower-plugin teos installation job

[sr-gi]

After #248, protoc needs to be manually installed. This would usually happen when creating the CLN cache job, however, we haven't re-recreated the cache just for that, so the command has also been temporarily added to the install teos job.

Once the cache is updated (e.g. after bumping the CLN version and updating the plugin to the new API), the command can be removed. ref: 7bae23e