gopls: use clear function for the clear postfix

Author: ALX99

gopls/internal/golang/completion/postfix_snippets.go

@@ -175,10 +175,8 @@ for {{.VarName .KeyType "k" | .Placeholder}}, {{.VarName .ElemType "v" | .Placeh
 	label:   "clear",
 	details: "clear map contents",
 	body: `{{if and (eq .Kind "map") .StmtOK -}}
-{{$k := (.VarName .KeyType "k")}}for {{$k}} := range {{.X}} {
-	delete({{.X}}, {{$k}})
-}
-{{end}}`,
+clear({{.X}})
+{{- end}}`,
 }, {
 	label:   "keys",
 	details: "create slice of keys",

gopls/internal/test/integration/completion/postfix_snippet_test.go

@@ -234,10 +234,7 @@ package foo
 
 func _() {
 	var foo map[string]int
-	for k := range foo {
-	delete(foo, k)
-}
-
+	clear(foo)
 }
 `,
 		},

gopls/internal/test/marker/testdata/completion/postfix.txt

@@ -84,7 +84,7 @@ func _() {
 	foo.fo //@snippet(" //", postfixFor, "for ${1:} := range foo {\n\t$0\n}")
 	foo.forr //@snippet(" //", postfixForr, "for ${1:}, ${2:} := range foo {\n\t$0\n}")
 	foo.rang //@snippet(" //", postfixRange, "for ${1:}, ${2:} := range foo {\n\t$0\n}")
-	foo.clear //@snippet(" //", postfixClear, "for k := range foo {\n\tdelete(foo, k)\n}\n")
+	foo.clear //@snippet(" //", postfixClear, "clear(foo)")
 	foo.keys //@snippet(" //", postfixKeys, "keys := make([]int, 0, len(foo))\nfor k := range foo {\n\tkeys = append(keys, k)\n}\n")
 }