Drop `use_web_ide_extension_marketplace` from `user_preferences`

MRs:

• User preferences: ignore use_web_ide_extension_... (!157526 - merged)
• Drop use_web_ide_extension_marketplace column (!159758 - merged)
• Remove all references of `use_web_ide_marketpla... (!166539 - merged)

Description

Following up from Create `extensions_marketplace_opt_in_status` f... (#455158 - closed), we should schedule use_web_ide_extension_marketplace to be dropped from the Db.

Acceptance Criteria

• This process is followed for the use_web_ide_extension_marketplace column on the user_preferences table.