build: ignore all the "Debug","Release" folders

Since there're still many "Debug" and "Release" folders in "deps" and
"tools", to make it more strict and totally ignore the generated obj
files, ignore all the files/folders under them.

Refs: #27210

PR-URL: #31565
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: David Carlier <devnexen@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

.gitignore

@@ -45,8 +45,8 @@
 /config_fips.gypi
 
 # === Rules for MSVS artifacts ===
-/Debug
-/Release
+Debug/
+Release/
 *.sln
 *.suo
 *.vcxproj*