install-mediawiki: improve debugging behavior
Two changes:
- Create a file to signal success
- Only sleep on previous failure if explicitly requested by the chart
This solves two issues.
If init containers are started again for a running env due to e.g.
the cluster being restarted, install-mediawiki
will simply succeed
and return instead of getting stuck for an hour in the sleep command.
Also, by default do not sleep and simply fail if a previous run
didn't succeed. The container will only sleep if explicitly requested
via debug.initContainers
Bug: T379358