[RUM-12158][V3] SR: Remove defaultPrivacyLevel

[sbarrio]

What does this PR do?

This PR removes the deprecated Session Replay configuration option defaultPrivacyLevel from SessionReplay.enable.

Motivation

This is an effort to simplify and streamline how users define their privacy settings for Session Replay.

Users should now rely on the granular privacy settings:

imagePrivacyLevel
touchPrivacyLevel
textAndInputPrivacyLevel

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests
• 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)
• If this PR is auto-generated, please make sure also to manually update the code related to the change