task(settings,content,auth): Add account uid to gling pings

[dschom]

Because

• We can decorate glean pings with raw uid

This pull request

• Adds account uid (when available) to glean pings

Issue that this pull request solves

Closes: FXA-10321

Checklist

Put an x in the boxes that apply

• My commit is GPG signed.
• If applicable, I have modified or added tests which pass locally.
• I have added necessary documentation (if appropriate).
• I have verified that my changes render correctly in RTL (if appropriate).

Screenshots (Optional)

Please attach the screenshots of the changes made in case of change in user interface.

Other information (Optional)

Asides from tests, I was able to manually validate account_uid was added to pings.

[dschom]

Not sure if subplat-backend should also be updated, but I went ahead and added for consistency.

[chenba]

@StaberindeZA

[chenba]

LGTM. Let's use user_id like you originally planned. Thanks!