[build] Disentangle bundling from 'is_debug' via 'devtools_bundle'

We want to enabling bundling (without minifcation) for debug builds.
This requires using a separate GN arg we call `devtools_bundle`.

Note that we keep GRD compression and minifcation for release/official
builds.

In a follow-up we'll rename the `grd_release_source_files` and
`grd_debug_source_files` in code and documentation to better reflect
the new reality.

Drive-by: Remove unused devtools_dcheck_always_on GN arg.

[email protected], [email protected]

Bug: 427899682
Change-Id: I7e0eec73853ae0e835011ae54906eedaf7ba59c1
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6678954
Reviewed-by: Alex Rudenko <[email protected]>
Reviewed-by: Philip Pfaffe <[email protected]>
Commit-Queue: Simon Zünd <[email protected]>
diff --git a/BUILD.gn b/BUILD.gn
index 3bf08d9..eeaaaca 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -90,7 +90,7 @@
 
 _expected_grd_files = []
 _expected_grd_files += grd_files_release_sources
-if (is_debug) {
+if (!devtools_bundle) {
   _expected_grd_files += grd_files_debug_sources
 }