Fix redacting the auth key when tailscale up fails

This patch redacts the authkey from `tailscale up` stderr output based
on `tailscale_authkey` directly instead of the `tskey.*` regex. The same
change was already applied for the stdout logging in artis3n#328.

tasks/install.yml

@@ -167,6 +167,6 @@
 
 - name: Install | Report redacted failure from "tailscale up"  # noqa: no-handler
   ansible.builtin.fail:
-    msg: "{{ tailscale_start.stderr | default () | regex_replace('tskey.*\\s', 'REDACTED ') | regex_replace('\\t', '') | split('\n') }}"
+    msg: "{{ tailscale_start.stderr | default () | regex_replace(tailscale_authkey, 'REDACTED') | regex_replace('\\t', '') | split('\n') }}"
   when:
     - tailscale_start is failed