[Fleet] Setup index.mapping.ignore_malformed in transforms too

[jsoriano]

Fleet configures index.mapping.ignore_malformed to true in some data streams, at least in the logs ones (#157184).

In these cases transforms that uses these data streams may fail because they don't ignore malformed fields.

Setup index.mapping.ignore_malformed also in transform indexes to avoid these issues.

Related issues:

• [TI_MISP] Transform logs-ti_misp.latest_ioc can enter on a FAILED state because of mapping conflicts. integrations#9360
• Replaces Allow index.mapping.ignore_malformed to be set inside index templates package-spec#730

[elasticmachine]

Pinging @elastic/fleet (Team:Fleet)