fix(template): use TrimSuffix instead of TrimRight to avoid over-stripping

TrimRight strips all trailing newlines which could affect templates
that intentionally end without a trailing newline (see #31948).
TrimSuffix removes at most one trailing newline, which is sufficient
to fix the double-newline regression from #32163.

Co-authored-by: Cloud-Architect-Emma <Cloud-Architect-Emma@users.noreply.github.com>
Signed-off-by: Cloud-Architect-Emma <your@email.com>

pkg/action/install.go

@@ -732,7 +732,7 @@ func writeToFile(outputDir string, name string, data string, appendData bool) er
 
 	defer f.Close()
 
-	_, err = fmt.Fprintf(f, "---\n# Source: %s\n%s\n", name, strings.TrimRight(data, "\n"))
+	_, err = fmt.Fprintf(f, "---\n# Source: %s\n%s\n", name, strings.TrimSuffix(data, "\n"))
 
 	if err != nil {
 		return err