refactor(core): Consistent use of HEADER_OFFSET (in ɵɵ* instructions only) (#39233)

IMPORTANT: `HEADER_OFFSET` should only be refereed to the in the `ɵɵ*` instructions to translate
instruction index into `LView` index. All other indexes should be in the `LView` index space and
there should be no need to refer to `HEADER_OFFSET` anywhere else.

PR Close #39233

goldens/size-tracking/integration-payloads.json

@@ -21,7 +21,7 @@
     "master": {
       "uncompressed": {
         "runtime-es2015": 1485,
-        "main-es2015": 147242,
+        "main-es2015": 146698,
         "polyfills-es2015": 36571
       }
     }