Deprecation log indexing relies on index templates to be present in
cluster state in order to create a data stream.
If a very early deprecation is emitted after node is started up and
templates are not loaded yet this can result in regular index with
default settings and mappings to be created.
To prevent this a bulk processor used for indexing deprecation logs
delays flushing until templates are loaded.

closes #80265

• Have you signed the contributor license agreement?
• Have you followed the contributor guidelines?
• If submitting code, have you built your formula locally prior to submission with gradle check?
• If submitting code, is your pull request against master? Unless there is a good reason otherwise, we prefer pull requests against master and will backport as needed.
• If submitting code, have you checked that your submission is for an OS and architecture that we support?
• If you are submitting this code for a class then read our policy for that.