#10295059 Preparations to relaunch 50% experiment with better tracks and data usage

Proposed Changes

• Change the wording in the input text when the user is presented with a different communication flow.
• Add new events when navigating to a different contact options
• When navigating to another flow, clear automatically the chat

Testing Instructions

• Ask Wapuu to connect with a HE or dislike a message.
• The input text field placeholder should change to “Continue chatting with Wapuu”
• Click on a contact option (either email, chat, or forum)
• Assert that the corresponding event is fired
• 
• Go back to Wapuu and assert that the chat has been cleared

Clear the flag add a minus symbol (flags=-wapuu)

• Assert that regular flows are still working as before; eg, not firing new events, behaving like normal, etc.

Pre-merge Checklist

• Has the general commit checklist been followed? (PCYsg-hS-p2)
• Have you written new tests for your changes?
• Have you tested the feature in Simple (P9HQHe-k8-p2), Atomic (P9HQHe-jW-p2), and self-hosted Jetpack sites (PCYsg-g6b-p2)?
• Have you checked for TypeScript, React or other console errors?
• Have you used memoizing on expensive computations? More info in Memoizing with create-selector and Using memoizing selectors and Our Approach to Data
• Have we added the “[Status] String Freeze” label as soon as any new strings were ready for translation (p4TIVU-5Jq-p2)?
• For changes affecting Jetpack: Have we added the “[Status] Needs Privacy Updates” label if this pull request changes what data or activity we track or use (p4TIVU-ajp-p2)?