Refactor Selenium Grid scaler

[VietND96]

Provide a description of what has been changed

1. Selenium Grid Scaler: Improve logic based on node stereotypes, node sessions and queue requests capabilities (#6080)

• Enhanced KEDA scaler behavior, addressing:
  • Node with different platformName scaling: Fixed incorrect scaling behavior when both Linux and Windows node stereotypes are present (#1925).
  • Excessive autoscaling: Resolved over-scaling of browser nodes (#2160).

2. Added one more parameter nodeMaxSessions (default is 1), to configure the scaler to be aligned with option --max-sessions (env var SE_NODE_MAX_SESSIONS) in the Node. It helps the calculation be better.
3. Selenium Grid Scaler: Support for Username and Password Authentication of Grid GraphQL endpoint (#6144)
4. Update all unit tests accordingly to the new GraphQL response.

Checklist

• 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 the documentation on (repo) (if applicable)
• Commits are signed with Developer Certificate of Origin (DCO - learn more)

Fixes #6144 Fixes #6080

Relates to SeleniumHQ/docker-selenium#2160, SeleniumHQ/docker-selenium#1925, #6047

[SpiritZhou]

/run-e2e selenium
Update: You can check the progress here

[VietND96]

Noted that we also set up some e2e tests in the downstream repo https://github.com/SeleniumHQ/docker-selenium/tree/trunk/.keda for the evaluation and feedback from community

[zroubalik]

/run-e2e selenium
Update: You can check the progress here

[zroubalik]

LGTM, this is really great, thanks for the contribution!