Closes https://github.com/zed-industries/zed/issues/37774 Bug in https://github.com/zed-industries/zed/pull/32927 Instead of using trigger characters to clear cached completions items, now we check if the query is empty to clear it. Turns out Emmet defines whole [alphanumeric as trigger characters](https://github.com/olrtg/emmet-language-server/blob/279be108725fb391c167690b697ce154fd32657b/index.ts#L116) which causes flickering. Clear on trigger characters was introduced to get rid of cached completions like in the case of "Parent.Foo.Bar", where "." is one of the trigger characters. This works still since "." is not part of `completion_query_characters` and hence we use it as a boundary while building the current query. i.e in this case, the query would be empty after typing ".", clearing cached completions. Release Notes: - Fixed issue where completions menu flashed on every keystroke in TSX files with emmet extension installed.