ingest/filtering: enable filtering by default

[sreuland]

What problem does your feature solve?

un-necessary configuration flag to enable ingestion filtering rather than default

What would you like to see?

ingestion filtering enabled by default, don't need to configure the runtime flag, remove --exp-enable-ingestion-filtering flag from the help output, but keep the flag definition. Log a warning message saying the flag is deprecated if it's present. find any references to the flag in the repo and remove them or document as deprecated.

There will be no filter rules created by default which results in effectively same end result, nothing filtered. Need to confirm this is the outcome when filtering enabled with no rules.

remove reference of the flag in the public ingestion docs

What alternatives are there?

set the --exp-enable-ingestion-filtering in horizon runtime config.

[mollykarcher]

Let's check the expected behavior when an unknown flag is sent; will installs fail or silently ignore it. This will impact how we want to roll it out - with deprecation warning or just hard remove