refactor(_comp_ltrim_colon_completions): simplify implementation

Author: akinomyoga

bash_completion

@@ -875,10 +875,7 @@ _comp_ltrim_colon_completions()
     if [[ $1 == *:* && $COMP_WORDBREAKS == *:* ]]; then
         # Remove colon-word prefix from COMPREPLY items
         local colon_word=${1%"${1##*:}"}
-        COMPREPLY=("${COMPREPLY[@]}")
-        while ((i-- > 0)); do
-            COMPREPLY[i]=${COMPREPLY[i]#"$colon_word"}
-        done
+        COMPREPLY=("${COMPREPLY[@]#"$colon_word"}")
     fi
 } # _comp_ltrim_colon_completions()