fix: Selenium Grid in case multiple scaler triggers are activate

[VietND96]

Implement strictly the condition to trigger the scaler in complex cases that Selenium Grid includes autoscaling Nodes (with multiple scaledObject with different triggers metadata), non-autoscaling Nodes, relay Nodes, and so on.

In general, update the scaler logic should be aligned with Selenium Grid core in DefaultSlotMatcher - which can be inspected https://github.com/SeleniumHQ/selenium/blob/trunk/java/src/org/openqa/selenium/grid/data/DefaultSlotMatcher.java

It is also recommended to set the browserName, browserVersion, and platformName to align across request capabilities, Node stereotype and scaler trigger params to have correct scaling behavior.

In terms of SlotMatcher in Grid, there is no value latest for the capability browserVersion. So, remove that value latest and keep the default value EMPTY.

For example, client sends the request (in Python binding)

options = ChromeOptions()
options.set_capability('platformName', 'Linux')
driver = webdriver.Remote(options=options, command_executor=SELENIUM_GRID_URL)

It is equivalent to scaler trigger params.

  triggers:
    - type: selenium-grid
      metadata:
        url: 'http://selenium-hub:4444/graphql'
        browserName: 'chrome'
        platformName: 'linux'

For example, client sends the request

options = ChromeOptions()
options.set_capability('platformName', 'Linux')
options.set_capability('browserVersion', '131.0')
driver = webdriver.Remote(options=options, command_executor=SELENIUM_GRID_URL)

The scaler trigger param should be aligned as

  triggers:
    - type: selenium-grid
      metadata:
        url: 'http://selenium-hub:4444/graphql'
        browserName: 'chrome'
        platformName: 'linux'
        browserVersion: '131.0'

Most people are using the popular browser node image from the project docker-selenium. In default Node stereotype, the short browser version is set for browserVersion, it might cause breaking backward compatiblity, or request without browserVersion could not trigger scaler anymore. Via SeleniumHQ/docker-selenium#2520, you can set SE_NODE_BROWSER_VERSION as empty to unset the default version (take newer docker image tag from that project, which contains the change onwards).

This also avoids multiple scalers, for example same browserName combines multiple browserVersion could have issue with overlapping in counting number of ongoing and pending sessions belonging to each scaler trigger.

In terms of Selenium Grid v4, it has a kind of Relay Node, which has capabilities to forward commands to the Appium instance. With this Node type, the browserName is optional. So, updating the trigger param browserName to optional.

Checklist

• 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 #

Relates to #

[JorTurFer]

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

[JorTurFer]

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

[VietND96]

Can you try e2e run one more time, I guess pull image could take time or reach pull limit rate...Here is result in my local

EXECUTION SUMMARY
##############################################
##############################################
Passed tests:
        Execution of tests/scalers/selenium/selenium_test.go, has passed after "one" attempts

[JorTurFer]

It looks like issue reaching the hub ->

scale_handler	error getting scale decision	***"scaledObject.Namespace": "selenium-test-ns", "scaledObject.Name": "chrome-selenium-test-so", "scaler": "seleniumGridScaler", "error": "error requesting selenium grid endpoint: Post \"[http://selenium-hub.selenium-test-ns:4444/graphql\](http://selenium-hub.selenium-test-ns:4444/graphql/)": dial tcp ***0.0.***5***.***4***:4444: connect: connection refused"***
github.com/***/keda/v***/pkg/scaling.(*scaleHandler).getScalerState
	/workspace/pkg/scaling/scale_handler.go:780
github.com/***/keda/v***/pkg/scaling.(*scaleHandler).getScaledObjectState.func***

I'm checking another issue in my local, once I finish I'll try to check this too