Fix to IsActive utility function in nodes package

[javuto]

Adding tests to the utility function IsActive for nodes and small fix to compare times in absolute values.

PR Overview

This PR fixes the logic in the IsActive utility function for the nodes package and adds tests to validate its behavior.

• Adjusted the time comparison in IsActive to use absolute values.
• Added tests to cover scenarios with recent and stale node states.

Reviewed Changes

File	Description
pkg/nodes/utils_test.go	Added test cases for validating the IsActive function behavior
pkg/nodes/utils.go	Updated time comparison logic to use absolute value for hours

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (2)

pkg/nodes/utils.go:9

• Consider adding input validation to ensure that the 'inactive' parameter is negative, as expected by the function logic.

func IsActive(n OsqueryNode, inactive int64) bool {

pkg/nodes/utils_test.go:11

• Consider using a fixed timestamp (e.g., via time.Date) in tests to ensure deterministic behavior.

now := time.Now()