[test][prefix][algorithms] Cleanup

Fixing:
- Empty optional fields
- Missing mandatory field
- Wrong additional field
- Wrong value type

beat/core/test/prefix/algorithms/schema/invalid_loop_output/1.json

@@ -3,7 +3,6 @@
     "language": "python",
     "api_version": 2,
     "type": "loop",
-    "splittable": false,
     "groups": [
         {
             "inputs": {

beat/core/test/prefix/algorithms/user/db_input_loop/1.json

@@ -22,7 +22,7 @@
     ],
     "parameters": {
         "threshold": {
-            "default": "9",
+            "default": 9,
             "type": "int8",
             "description": "Value that will change loop result"
         }

beat/core/test/prefix/algorithms/user/db_input_loop_user/1.json

@@ -4,9 +4,6 @@
     "api_version": 2,
     "type": "loop_user",
     "splittable": false,
-    "parameters": {
-
-    },
     "groups": [
         {
             "inputs": {

beat/core/test/prefix/algorithms/user/for_dep/1.json

@@ -17,6 +17,5 @@
                 }
             }
         }
-    ],
-    "uses": {}
+    ]
 }

beat/core/test/prefix/algorithms/user/integers_add/1.json

@@ -18,7 +18,7 @@
   ],
   "parameters": {
     "offset": {
-      "default": "1",
+      "default": 1,
       "type": "int32"
     }
   },

beat/core/test/prefix/algorithms/user/labelled_integers_sum/1.json

@@ -18,7 +18,5 @@
                 }
             }
         }
-    ],
-    "parameters": {
-    }
+    ]
 }

beat/core/test/prefix/algorithms/user/shell_exec/1.json

@@ -11,7 +11,8 @@
   ],
   "parameters": {
     "command": {
-      "type": "string"
+      "type": "string",
+      "default": ""
     }
   },
   "results": {