feat(compiler-cli): no longer re-export external symbols by default (#28633)

With #28594 we refactored the `@angular/compiler` slightly to
allow opting out from external symbol re-exports which are
enabled by default.

Since symbol re-exports only benefit projects which have a
very strict dependency enforcement, external symbols should
not be re-exported by default as this could grow the size of
factory files and cause unexpected behavior with Angular's
AOT symbol resolving (e.g. see: #25644).

Note that the common strict dependency enforcement for source
files does still work with external symbol re-exports disabled,
but there are also strict dependency checks that enforce strict
module dependencies also for _generated files_ (such as the
ngfactory files). This is how Google3 manages it's dependencies
and therefore external symbol re-exports need to be enabled within
Google3.

Also "ngtsc" also does not provide any way of using external symbol
re-exports, so this means that with this change, NGC can partially
match the behavior of "ngtsc" then (unless explicitly opted-out).

As mentioned before, internally at Google symbol re-exports need to
be still enabled, so the `ng_module` Bazel rule will enable the symbol
re-exports by default when running within Blaze.

Fixes #25644.

PR Close #28633

packages/bazel/src/ng_module.bzl

@@ -245,6 +245,13 @@ def _ngc_tsconfig(ctx, files, srcs, **kwargs):
         "enableSummariesForJit": is_legacy_ngc,
         "enableIvy": _enable_ivy_value(ctx),
         "fullTemplateTypeCheck": ctx.attr.type_check,
+        # In Google3 we still want to use the symbol factory re-exports in order to
+        # not break existing apps inside Google. Unlike Bazel, Google3 does not only
+        # enforce strict dependencies of source files, but also for generated files
+        # (such as the factory files). Therefore in order to avoid that generated files
+        # introduce new module dependencies (which aren't explicitly declared), we need
+        # to enable external symbol re-exports by default when running with Blaze.
+        "createExternalSymbolFactoryReexports": (not _is_bazel()),
         # FIXME: wrong place to de-dupe
         "expectedOut": depset([o.path for o in expected_outs]).to_list(),
     }