[Relaunch][NTP Customization] Refactor feed metrics.

This CL prepares for the addition of metrics to the Discover Feed bottom sheet within the NTP Customization project. It includes the following changes:
1. Delete metrics related to feed controls action.
2. Corrected inconsistencies in metric recording within FeedManagementMediator when users click the Following, Hidden sections.
3. Modified the metric recording for FeedUserActionType to exclude StreamKind for feed management actions, as it's unnecessary and will be partially removed after the Following feed deprecation. A new function was added to achieve this.

Bug: 404592444
Change-Id: I483edf5c5d99ca53691bd233b7f9d796ca5222aa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6394967
Reviewed-by: Jian Li <jianli@chromium.org>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Commit-Queue: Xinyi Ji <xinyiji@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1438391}