Built in variable gl_DrawID is exposed to ESSL1 with
a suffix, when the variable is the exact same. No need
to do this.

Bug: angleproject:3805
Change-Id: I63c71791bb6a0e8aa7b644171a3f5a81099eddc0
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1762359Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Clemen Deng <clemendeng@google.com>