feat: support scaling direction-aware cooldown for task auto-scalers

[jtuglu1]

Description

Adds support for configuring different cooldowns for scaling direction. While both scaling actions do cause temporary disruption to ingestion, scaling down can cause more disruption than scaling up due to having less resources than when you started to recover from lag. Therefore, to allow for aggressive scale up while having a more conservative scale-down approach, this adds configuration for cool down period for both directions. Cool down for a specific scaling direction is evaluated as follows:

1. minTriggerScaleUpActionFrequencyMillis/minTriggerScaleDownActionFrequencyMillis
2. minTriggerScaleActionFrequencyMillis
3. The default of 600000.

This also does the following:

1. Cleans up the core scaling logic to be more clear/readable
2. Adds a custom ScaleActionSupplier which makes the contract clear for auto-scalers who want to implement it.
3. Fixes a few notification bugs, namely emitting/logging metrics irrespective of whether we are actually planning to scale or not (e.g. auto-scaler function returns value != -1, but that value is equal to the current task count).

Release note

Adds support for configuring different cooldowns for scaling direction for streaming task auto-scalers.

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This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.