[Connector API] Change UpdateConnectorFiltering API to have better defaults

[efegurkan]

This changes validation behaviour for rules to have better defaults instead of throwing. The following cases changed to not throw:

• When "rules" is an empty array, instead of throwing we attach a default rule
• When "rules" have items but doesn't have default rule, we append a default rule.
• Rules array will be ordered and default will be moved as the last

[elasticsearchmachine]

Pinging @elastic/ent-search-eng (Team:Enterprise Search)

[elasticsearchmachine]

Hi @efegurkan, I've created a changelog YAML for you.

[elasticsearchmachine]

Hi @efegurkan, I've created a changelog YAML for you.