Need to clear user cache after running direct query to update user displayname

[prettyboymp]

The xprofile_sync_wp_profile() function runs a direct query to update the user's display name. clean_user_cache($user_id) needs to be called after that query or the change will never show if object cache is being used.

Ref: ​https://github.com/buddypress/BuddyPress/blob/a4890c8a2c410ae1d6b6245117c548bac05b5b21/src/bp-xprofile/bp-xprofile-functions.php#L806

[johnjamesjacoby]

Confirmed.

We do clean other caches in bp-xprofile-cache.php but the core user objects are missed.

Plausible there's more tuning required, as many of our cache busting actions are hooked at priority 10 with other functions that are also hooked at 10, but maybe too-soon or too-late depending on the context.

[johnjamesjacoby]

This is important enough to fit into 2.6 during the beta period, and will be a small enough code change that my confidence level that it will not cause additional breakage is very high.

[djpaul]

In 10857:

xprofile: remove direct SQL query when syncing BP profile to WP, and clear BP user cache.

When the user updates their profile name, and xprofile syncing is enabled (the default), we update the display_name property of the WordPress user. We remove the direct query to help prevent WordPress having a stale cache.

We also need to clear our own legacy user cache object so that bp_displayed_user_fullname returns accurate data.

Fixes #7050