segregate test files in a3p proposals (#10853)

refs: Agoric/agoric-3-proposals#115

## Description

A3P is getting this feature,
- Agoric/agoric-3-proposals#213

This PR takes advantage of it for a3p-integration tests.

### Security Considerations
none, just test

### Scaling Considerations
none, just test

### Documentation Considerations
none

### Testing Considerations
per se

### Upgrade Considerations
none, just test

a3p-integration/package.json

@@ -16,7 +16,7 @@
     "doctor": "yarn synthetic-chain doctor"
   },
   "dependencies": {
-    "@agoric/synthetic-chain": "^0.4.3",
+    "@agoric/synthetic-chain": "^0.5.1",
     "@types/better-sqlite3": "^7.6.11"
   },
   "packageManager": "[email protected]",

a3p-integration/proposals/f:fast-usdc/package.json

@@ -3,7 +3,7 @@
     "source": "subdir",
     "sdk-generate": [
       "fast-usdc/start-fast-usdc.build.js submission --net A3P_INTEGRATION --noNoble",
-      "fast-usdc/add-operators.build.js add-operators --oracle oracleNew:agoric1hmdue96vs0p6zj42aa26x6zrqlythpxnvgsgpr"
+      "fast-usdc/add-operators.build.js test/add-operators --oracle oracleNew:agoric1hmdue96vs0p6zj42aa26x6zrqlythpxnvgsgpr"
     ],
     "type": "/agoric.swingset.CoreEvalProposal"
   },
@@ -12,7 +12,7 @@
   "dependencies": {
     "@agoric/client-utils": "dev",
     "@agoric/fast-usdc": "dev",
-    "@agoric/synthetic-chain": "^0.4.3",
+    "@agoric/synthetic-chain": "^0.5.1",
     "@endo/init": "^1.1.7",
     "agoric": "dev",
     "ava": "^5.3.1"
@@ -21,6 +21,7 @@
     "concurrency": 1,
     "timeout": "2m",
     "files": [
+      "test/**/*.test.*",
       "!submission"
     ]
   },

a3p-integration/proposals/f:fast-usdc/test.sh

@@ -1,6 +1,10 @@
 #!/bin/bash
 set -euo pipefail
 
+# segregate so changing these does not invalidate the proposal image
+# à la https://github.com/Agoric/agoric-3-proposals/pull/213
+cd test
+
 echo AVAILABLE WALLETs
 agd query vstorage children published.wallet