Simplify renovate.json, better reflect working renovate.json

Takes from https://repo1.dso.mil/dsop/container-hardening-tools/renovate/renovate renovate.json since it seems to be functioning properly at this time.

hardening_manifest.yaml

@@ -14,7 +14,7 @@ tags:
 # Build args passed to Dockerfile ARGs
 args:
   BASE_IMAGE: "opensource/nodejs/nodejs14"
-  BASE_TAG: "14.17.0"
+  BASE_TAG: "14.17.1"
 
 # Docker image labels
 labels:

renovate.json

@@ -5,24 +5,16 @@
   "baseBranches": [
     "development"
   ],
+  "automerge": true,
+  "gitLabAutomerge": true,
   "regexManagers": [{
-      "fileMatch": [
-        "^Dockerfile$"
-      ],
-      "matchStrings": [
-        "version=\"(?<currentValue>.*?)\""
-      ],
-      "depNameTemplate": "mitre/heimdall2",
-      "datasourceTemplate": "docker"
-    },
-    {
       "fileMatch": [
         "^hardening_manifest.yaml$"
       ],
       "matchStrings": [
-        "org\\.opencontainers\\.image\\.version:\\s+\"(?<currentValue>.+?)\""
+        "BASE_TAG:\\s+\"(?<currentValue>.*?)\""
       ],
-      "depNameTemplate": "mitre/heimdall2",
+      "depNameTemplate": "registry1.dso.mil/ironbank/opensource/nodejs/nodejs14",
       "datasourceTemplate": "docker"
     },
     {
@@ -30,6 +22,7 @@
         "^hardening_manifest.yaml$"
       ],
       "matchStrings": [
+        "org\\.opencontainers\\.image\\.version:\\s+\"(?<currentValue>.+?)\"",
         "tags:\\s+-\\s+\"(?<currentValue>.+?)\""
       ],
       "depNameTemplate": "mitre/heimdall2",