Build modules: no cap of their own; a step's threads are its part of the node's one share (ADR 0553, issue 1806)

Review round 1: a cap per module let three build modules take three shares
of the node. The share is now one node value held by the node-engine's
yielding slice; each step divides it by every build slot of the node, from the
composer's words, or assumes every build seat at its own capacity without them.

modules/mesh-build-node/module.json

@@ -25,12 +25,6 @@
       "description": "How many asks of the Node build seat this module runs at once on each node, as node=asks pairs separated by commas, such as shanks=3,ace=2 (novox/hq ADR 0525 §5); a node set to 0 pulls nothing, a node not named runs one at a time. The control-node and the laptop build nothing.",
       "pattern": "|[a-z0-9_-]+=[0-9]+(,[a-z0-9_-]+=[0-9]+)*",
       "default": "shanks=3,ace=2,g14=0,novox=0"
-    },
-    "cpu-cap": {
-      "type": "string",
-      "description": "The most of each node's processors this module's builds may take, as node=percent pairs separated by commas, such as shanks=50,ace=75 (novox/hq issue 1806); a node not named takes 50. The node-engine holds the module's runtime to it as a CPU quota, at idle priority, and each build step starts no more threads than its part of it.",
-      "pattern": "|[a-z0-9_-]+=([1-9]|[1-9][0-9]|100)%?(,[a-z0-9_-]+=([1-9]|[1-9][0-9]|100)%?)*",
-      "default": "shanks=50,g14=50,ace=75"
     }
   },
   "tools": [
@@ -105,7 +99,7 @@
       "path": "${dir:state}/settings.json",
       "mode": "0600",
       "owner": "mesh-build-node",
-      "takes-config": ["capacity", "cpu-cap"],
+      "takes-config": ["capacity"],
       "merge": "json",
       "template": "files/settings.json"
     },