bug#30056: 25.3; battery-mode-line-string missing leading space

[Juri Linkov]

>> A less breakey change is to institute a different rule: All
>> `global-mode-string' elements have to have a trailing space.  That'll be
>> less breakey, but may add spaces before the "----" in terminals.
>
> I've now done this, and it doesn't add spaces before the "---" bit.
>
> I grepped through the Emacs tree to see whether any other packages have
> problems in this area, but the ones I skimmed seemed to already adhere
> to this previous non-convention (i.e., they added a space at the end).
> But I may have missed some, of course.

This change broke tab-bar.el that expected that the default value of
mode-line-misc-info contains (global-mode-string ("" global-mode-string " ")).

BTW, 9dfa94aed1 duplicated 3 paragraphs in etc/NEWS.