Sometimes user activity score is not increasing for kClickedBackOrForwardNavigationButtons events

[btlechowski]

Some kClickedBackOrForwardNavigationButtons events are not processed for ads user activity

Steps to Reproduce

Follow steps from User Activity - Custom values - kClickedBackOrForwardNavigationButtons from https://github.com/brave/internal/issues/763

Actual result:

Some navigation events are processed. Some are ignored.

Expected result:

All navigation events are processed

Reproduces how often:

Easily reproduced

Brave version (brave://version info)

Brave	1.23.63 Chromium: 89.0.4389.114 (Official Build) beta (64-bit)
Revision	1ea76e193b4fadb723bfea2a19a66c93a1bc0ca6-refs/branch-heads/4389@{#1616}
OS	Ubuntu 18.04 LTS

cc @brave/legacy_qa @tmancey @moritzhaller @jsecretan

[tmancey]

Discussed with @btlechowski and working as expected. Thanks