Fix some nightly tests flakiness

[0xnm]

What does this PR do?

This change fixes some flakiness in our tests:

• Some tests rely on the action.name assertion, but in case of action.type=back there is no action.name, only action.target.name. So we need to exclude back action type from such tests.
• With ♻️ [RUMF-1368] use the PointerDown event target for click actions browser-sdk#1731 browser-sdk requires an element to have pointerdown event before the actual click to register RUM action. The change is done instrumented test to add the necessary event.

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Make sure you discussed the feature or bugfix with the maintaining team in an Issue
• Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)