Change default for frequent-loops-enabled flag

[kawych]

What type of PR is this?

What this PR does / why we need it:

Frequent loops is a small optimization to avoid unnecessary scale-up delays. Changing default value to true with the ultimate goal to deprecate the flag and remove unused code.

NONE

[k8s-ci-robot]

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[jackfrancis]

Thanks @kawych for introducing and continuing to move this feature forward!

Before we turn this on by default we will want to significantly reinforce unit test coverage.

I notice that the PR history for this feature does not include the addition of any unit tests to validate and protect the new and changed behaviors to Cluster Autoscaler:

• Add an option to trigger iterations more frequently #6589
• Add support for frequent loops when provisioningrequest is encountered in last iteration #7418
• Improve frequent loops when only one of activities is productive #7679

(In addition, a prior version of #7418 was merged and then reverted.)

Can you submit a separate PR with UT coverage of the changes above? Once we improve our tests we can make a plan for considering enabling by default.

cc @gjtempleton @x13n @towca @aleksandra-malinowska

[jackfrancis]

/hold

for further discussion and better UT coverage of frequent-loops-enabled code paths

[x13n]

UT are probaby a good idea here. Also, the release note shouldn't be NONE, this is changing default value for a flag most users are likely not specifying today.