fix(aws): allow empty prefix and suffix in prompt function (#10744)

Fixes #10744

plugins/aws/aws.plugin.zsh

@@ -158,7 +158,7 @@ compctl -K _aws_profiles asp acp aws_change_access_key
 # AWS prompt
 function aws_prompt_info() {
   [[ -n "$AWS_PROFILE" ]] || return
-  echo "${ZSH_THEME_AWS_PREFIX:=<aws:}${AWS_PROFILE:gs/%/%%}${ZSH_THEME_AWS_SUFFIX:=>}"
+  echo "${ZSH_THEME_AWS_PREFIX=<aws:}${AWS_PROFILE:gs/%/%%}${ZSH_THEME_AWS_SUFFIX=>}"
 }
 
 if [[ "$SHOW_AWS_PROMPT" != false && "$RPROMPT" != *'$(aws_prompt_info)'* ]]; then