hive ui: remove the counters on the tabs

The pills on 4G3NTS, R3BU1LD QU3U3 and K3PT ST4T3, the poll that fed them, the
two count helpers, their styles, and the tab strip's unused badge option.

frontend/packages/dashboard/src/index.html

@@ -27,7 +27,6 @@
           data-tab="agents"
         >
           <span class="tab-label">◆ 4G3NTS ◆</span>
-          <span class="tab-count" id="tab-count-agents" hidden></span>
         </a>
         <!-- The build lifecycle is two tabs here (builds.js): the rebuild
            queue with its live log, and the build log history. Kept state
@@ -41,7 +40,6 @@
           data-tab="rebuild"
         >
           <span class="tab-label">◆ R3BU1LD QU3U3 ◆</span>
-          <span class="tab-count" id="tab-count-rebuild" hidden></span>
         </a>
 
         <a
@@ -63,7 +61,6 @@
           data-tab="kept"
         >
           <span class="tab-label">◆ K3PT ST4T3 ◆</span>
-          <span class="tab-count" id="tab-count-kept" hidden></span>
         </a>
 
         <!-- (Peer hives are no longer a tab — they render as a headline