Use a copy of the dawn_end2end_tests target while it is being moved

//third_party/dawn:dawn_end2end_tests is being moved under
//third_party/dawn/src/tests. gn_isolate_map always needs to point to a
valid "executable" GN target so tricks using proxy groups don't work to
rename. Instead the test executable has been duplicated with the _tmp
version that can be used while the non-_tmp version is moved under the
correct directory.

Bug: chromium:1064305
Change-Id: Ic74f6df2c031cf0a40eb741a58c5f0e4cabd8ea9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2146535Reviewed-by: Kenneth Russell <kbr@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#758580}

testing/buildbot/gn_isolate_map.pyl

@@ -724,8 +724,8 @@
     "label": "//crypto:crypto_unittests",
     "type": "console_test_launcher",
   },
-  "dawn_end2end_tests": {
-    "label": "//third_party/dawn:dawn_end2end_tests",
+  "dawn_end2end_tests_tmp": {
+    "label": "//third_party/dawn/src/tests:dawn_end2end_tests_tmp",
     "type": "raw",
   },
   "dawn_perf_tests": {

testing/buildbot/test_suites.pyl

@@ -1893,7 +1893,7 @@
           '--no-use-spvc',
           '--no-use-spvc-parser',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_skip_validation_tests': {
         'desktop_args': [
@@ -1902,7 +1902,7 @@
           '--test-launcher-retry-limit=0',
           '--skip-validation',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_tests': {
         'desktop_args': [
@@ -1910,6 +1910,7 @@
           # Dawn test retries deliberately disabled to prevent flakiness.
           '--test-launcher-retry-limit=0',
         ],
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_use_spvc_parser_tests': {
         'desktop_args': [
@@ -1919,7 +1920,7 @@
           '--use-spvc',
           '--use-spvc-parser',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_use_spvc_tests': {
         'desktop_args': [
@@ -1929,7 +1930,7 @@
           '--use-spvc',
           '--no-use-spvc-parser',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_validation_layers_tests': {
         'desktop_args': [
@@ -1938,7 +1939,7 @@
           '--test-launcher-retry-limit=0',
           '--enable-backend-validation',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_wire_tests': {
         'desktop_args': [
@@ -1947,7 +1948,7 @@
           '--test-launcher-retry-limit=0',
           '--use-wire',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
     },
 
@@ -1962,7 +1963,7 @@
           '--no-use-spvc',
           '--no-use-spvc-parser',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_skip_validation_tests': {
         'desktop_args': [
@@ -1971,7 +1972,7 @@
           '--test-launcher-retry-limit=0',
           '--skip-validation',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_tests': {
         'desktop_args': [
@@ -1979,6 +1980,7 @@
           # Dawn test retries deliberately disabled to prevent flakiness.
           '--test-launcher-retry-limit=0',
         ],
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_use_spvc_parser_tests': {
         'desktop_args': [
@@ -1988,7 +1990,7 @@
           '--use-spvc',
           '--use-spvc-parser',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_use_spvc_tests': {
         'desktop_args': [
@@ -1998,7 +2000,7 @@
           '--use-spvc',
           '--no-use-spvc-parser',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_validation_layers_tests': {
         'desktop_args': [
@@ -2007,7 +2009,7 @@
           '--test-launcher-retry-limit=0',
           '--enable-backend-validation',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
       'dawn_end2end_wire_tests': {
         'desktop_args': [
@@ -2016,7 +2018,7 @@
           '--test-launcher-retry-limit=0',
           '--use-wire',
         ],
-        'test': 'dawn_end2end_tests',
+        'test': 'dawn_end2end_tests_tmp',
       },
       'gl_tests': {
         'desktop_args': [