refactor(forms): get rid of duplicate functions (#38371)

This commit performs minor refactoring in Forms package to get rid of duplicate functions.
It looks like the functions were duplicated due to a slightly different type signatures, but
their logic is completely identical. The logic in retained functions remains the same and now
these function also accept a generic type to achieve the same level of type safety.

PR Close #38371

packages/core/test/bundling/forms/bundle.golden_symbols.json

@@ -701,9 +701,6 @@
   {
     "name": "_keyMap"
   },
-  {
-    "name": "_mergeErrors"
-  },
   {
     "name": "_noControlError"
   },
@@ -914,6 +911,9 @@
   {
     "name": "executeTemplate"
   },
+  {
+    "name": "executeValidators"
+  },
   {
     "name": "executeViewQueryFn"
   },
@@ -1346,6 +1346,9 @@
   {
     "name": "mergeAll"
   },
+  {
+    "name": "mergeErrors"
+  },
   {
     "name": "mergeHostAttribute"
   },
@@ -1401,10 +1404,7 @@
     "name": "noop"
   },
   {
-    "name": "normalizeAsyncValidator"
-  },
-  {
-    "name": "normalizeValidator"
+    "name": "normalizeValidators"
   },
   {
     "name": "observable"