fix issues on action runners page (#27226)

- switch from some weird status badge to label
- translate untranslated `Reset registration token` string
- change documentation link from act_runner README to Gitea Docs site
- fix "No runners available" message width
- use `ctx.Locale.Tr` where possible


![grafik](https://github.com/go-gitea/gitea/assets/47871822/65547228-f9ed-4f80-9cfd-df5e55513a44)

web_src/css/actions.css

@@ -18,12 +18,6 @@
   margin-right: 1em;
 }
 
-.runner-container .runner-status-online {
-  padding: 0.3em 0.5em;
-  background-color: var(--color-green);
-  color: var(--color-white);
-}
-
 .runner-container .runner-new-text {
   color: var(--color-white);
 }