themes: fix prompt verbosity on window resize

%_ is a prompt expansion sequence that expands to the status of the parser.
This means that on window resize, the status of the execution of the
window resize hook (TRAPWINCH) would be displayed while reloading the
prompt line. This looked like cmdand cursh$ or then$ depending on the
body of the TRAPWINCH function.

Fixes #7262

themes/dst.zsh-theme

@@ -11,6 +11,6 @@ function prompt_char {
 PROMPT='%(?, ,%{$fg[red]%}FAIL%{$reset_color%}
 )
 %{$fg[magenta]%}%n%{$reset_color%}@%{$fg[yellow]%}%m%{$reset_color%}: %{$fg_bold[blue]%}%~%{$reset_color%}$(git_prompt_info)
-%_ $(prompt_char) '
+$(prompt_char) '
 
 RPROMPT='%{$fg[green]%}[%*]%{$reset_color%}'

themes/gentoo.zsh-theme

@@ -2,7 +2,7 @@ function prompt_char {
 	if [ $UID -eq 0 ]; then echo "#"; else echo $; fi
 }
 
-PROMPT='%(!.%{$fg_bold[red]%}.%{$fg_bold[green]%}%n@)%m %{$fg_bold[blue]%}%(!.%1~.%~) $(git_prompt_info)%_$(prompt_char)%{$reset_color%} '
+PROMPT='%(!.%{$fg_bold[red]%}.%{$fg_bold[green]%}%n@)%m %{$fg_bold[blue]%}%(!.%1~.%~) $(git_prompt_info)$(prompt_char)%{$reset_color%} '
 
 ZSH_THEME_GIT_PROMPT_PREFIX="("
 ZSH_THEME_GIT_PROMPT_SUFFIX=") "

themes/tjkirch.zsh-theme

@@ -10,6 +10,6 @@ function prompt_char {
 PROMPT='%(?, ,%{$fg[red]%}FAIL: $?%{$reset_color%}
 )
 %{$fg[magenta]%}%n%{$reset_color%}@%{$fg[yellow]%}%m%{$reset_color%}: %{$fg_bold[blue]%}%~%{$reset_color%}$(git_prompt_info)
-%_$(prompt_char) '
+$(prompt_char) '
 
 RPROMPT='%{$fg[green]%}[%*]%{$reset_color%}'

themes/tjkirch_mod.zsh-theme

@@ -8,6 +8,6 @@ function prompt_char {
 }
 
 PROMPT='%(?,,%{$fg[red]%}FAIL: $?%{$reset_color%}
-)%{$fg[magenta]%}%n%{$reset_color%}@%{$fg[yellow]%}%m%{$reset_color%}: %{$fg_bold[blue]%}%~%{$reset_color%}$(git_prompt_info) %_$(prompt_char) '
+)%{$fg[magenta]%}%n%{$reset_color%}@%{$fg[yellow]%}%m%{$reset_color%}: %{$fg_bold[blue]%}%~%{$reset_color%}$(git_prompt_info) $(prompt_char) '
 
 RPROMPT='%{$fg[green]%}[%*]%{$reset_color%}'