apk_operations.py: Don't look for .mapping file for release builds

Although proguard is run in release, incremental install always uses the
debug dex files, and we so we don't bother running proguard.

This elimnates a FileNotFound log message when launching an apk that was
build with is_java_debug=false incremental_install=true

Change-Id: I5a955ca2b076ebd1bc0f13a28191b72364603ebe
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2142633
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Peter Wen <wnwen@chromium.org>
Commit-Queue: Peter Wen <wnwen@chromium.org>
Cr-Commit-Position: refs/heads/master@{#757562}

build/config/android/rules.gni

@@ -3284,7 +3284,7 @@ if (enable_java_templates) {
         _generated_script = "$root_build_dir/bin/${invoker.target_name}"
         script = "//build/android/gyp/create_apk_operations_script.py"
         outputs = [ _generated_script ]
-        if (_proguard_enabled) {
+        if (_proguard_enabled && !_incremental_apk) {
           # Required by logcat command.
           data_deps = [ "//build/android/stacktrace:java_deobfuscate" ]
           data = [ "$_final_apk_path.mapping" ]