Don't flush when completion items less than two

[adoyle-h]

I'm using latest version of fzf-tab with bash 5.2.2.

Description

When only one completion item, the flush of 'Loading matches ...'

When no completion matched, the flush still exists,

What I expect

No flush and no window pop up when the size of completion items less than two.

[lincheney]

Not sure this is truly fixable Bash/readline clears the prompt line before the keybind function is run. The flicker is unavoidable. See https://github.com/lincheney/fzf-tab-completion#custom-loading-message