Consider configuring failIfNotFullyCacheable to true by default in the composite workflows

[erichaagdev]

failIfNotFullyCacheable: true should be the default behavior and failIfNotFullyCacheable: false should be the exception.

If a user forgets to configure failIfNotFullyCacheable: true they will have a false sense of security thinking their build is optimized when it may not be.

This would be a breaking change, but only if failIfNotFullyCacheable is not already configured and the user's build has cache misses. It's reasonable to assume those cases are a misconfiguration.