Odoo Release Updates

[IMP] *: remove unnecessary button "Discard" labels

[REM] web: legacy test utils

[IMP] *: rename "Cancel" to "Discard"

[REF] mail, project: remove `_thread_to_store` function

[FIX] web,mail: fix concurrency in relational model

[IMP] mail: always search display_name and email in recipients input

[FIX] html_editor,mail: optionally disable banner commands

[IMP] mail: shorten long record names in notifications

[IMP] mail: better subscription message

[IMP] mail: fix composer dialog to 75vw

[IMP] mail: hide field highlight for body in mail composer

[IMP] mail,*: remove MailThreadCC

[FIX] mail: add test for mention suggestions in group-restricted channel

[FIX] mail: ondelete operations during module uninstallation

[FIX] orm: make ondelete decorator work as documented

[IMP] web: edit_tags_list

[IMP] mail: show private placeholder for empty group_ids using falsy_value_label

[FIX] mail: fix cropped badge

[IMP] mail: run all discuss tests with server version 99.9

[FIX] mail: avoid reverting the warning activity filter

[REF] mail: localStorage=true for 'voiceActivationThreshold'

[REF] mail: localStorage=true for showOnlyVideo

[REF] mail: localStorage=true for blur intensity settings

[REM] mail: drop obsolete gif picker code

[REF] mail: localStorage=true for 'deviceId'

[FIX] mail: handle mentions without base container

[FIX] mail: mockUserAgent usage

[FIX] mail: delete mention correctly

[REF] mail: move displayName to channel

[FIX] im_livechat, mail: missing bus subscription for non-member channels