Exclude nativeImageSource.js instead of matching [Nn]

Summary:
The change to this glob by D30266076 (f1b4748a7c) lines up suspiciously to a non-reproducible failure in the sources to the rules that use this glob. Changing to see if it mitigates the issue.

See https://fb.workplace.com/groups/askbuck/posts/6473961645985729/?comment_id=6476777799037447&reply_comment_id=6477737555608138

Changelog: [Internal]

Reviewed By: yungsters

Differential Revision: D30361375

fbshipit-source-id: af7b7fe553364fc1d7012bea8d00bf02ee2804fa

tools/build_defs/oss/rn_codegen_defs.bzl

@@ -39,9 +39,10 @@ def rn_codegen(
 
         spec_srcs = native.glob(
             [
-                src_prefix + "**/[Nn]ative*.js",
+                src_prefix + "**/Native*.js",
             ],
             exclude = [
+                src_prefix + "**/nativeImageSource.js",
                 "**/__*__/**",
             ],
         )