Revert "build: Generate gn_logs.txt"

This reverts commit 4abc704.

Reason for revert: breaks ANGLE to Skia auto roller: https://skia-review.googlesource.com/c/skia/+/930206

Original change's description:
> build: Generate gn_logs.txt
>
> This is necessary to make Siso builds work for angle.
> See https://crrev.com/c/6083212
>
> Bug: b/385244283
> Fixed: b/385244283
> Change-Id: I6bc6d82744106cce1c358f415e53ad842241b567
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6108522
> Commit-Queue: Roman Lavrov <[email protected]>
> Auto-Submit: Junji Watanabe <[email protected]>
> Reviewed-by: Roman Lavrov <[email protected]>

Bug: b/385244283
Change-Id: I4106d696c8f7b5db9fba1814b04c2c5c404e9413
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/6125598
Bot-Commit: Rubber Stamper <[email protected]>
Auto-Submit: Yuxin Hu <[email protected]>
Commit-Queue: Yuxin Hu <[email protected]>

BUILD.gn

@@ -1845,17 +1845,3 @@ group("angle_static") {
     ":translator",
   ]
 }
-
-# GN evaluates each .gn file once per toolchain, so restricting to default
-# toolchain will ensure write_file() is called only once.
-if (current_toolchain == default_toolchain) {
-  import("//build/gn_logs.gni")
-
-  # Write debug logs to gn_logs.txt.
-  _lines = [
-             "Generated during 'gn gen' by //BUILD.gn.",
-             "",
-           ] + build_gn_logs
-
-  write_file("$root_build_dir/gn_logs.txt", _lines)
-}