fix: Selenium Grid scaler logic on platformName is set empty or any

[VietND96]

When Node stereotype set "platformName": "" (empty), node started up and registered to Hub with converting to "platformName": "windows". Similarly, the same behavior in session capabilities. This unexpected behavior impacts the scaler in counting the pending and ongoing sessions.
This issue is fixed in Grid core SeleniumHQ/selenium#15036 (platformName is empty should be considered as enum ANY instead of WINDOWS). Available from 4.28.0 onwards.

The incoming request with setting capability "platformName": "any" or not set. It will be assigned to any Node with the stereotype platformName: any or not set.
So, updating the scaler condition to be aligned with the same behavior.

Checklist

• When introducing a new scaler, I agree with the scaling governance policy
• I have verified that my change is according to the deprecations & breaking changes policy
• Tests have been added
• Changelog has been updated and is aligned with our changelog requirements
• A PR is opened to update our Helm chart (repo) (if applicable, ie. when deployment manifests are modified)
• A PR is opened to update the documentation on (repo) (if applicable)
• Commits are signed with Developer Certificate of Origin (DCO - learn more)

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