[fuchsia] Uprev test-scripts with FUCHSIA_READELF env

Copied from http://go/dart-reviews/421761 with the essential fix to
make it work.

1) Add the env to select the right readelf.
2) Remove the removal of arch/, it's referred by meta.json.

Cq-Include-Trybots: luci.dart.try:vm-fuchsia-release-x64-try,vm-fuchsia-release-arm64-try
Bug: b/407890258, b/338009514
Change-Id: Ib7ae646e57082d310d3d76ca16834faefb888201
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/421881
Auto-Submit: Zijie He <zijiehe@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>

DEPS

@@ -546,7 +546,7 @@ deps = {
     "packages": [
       {
       "package": "chromium/fuchsia/test-scripts",
-      "version": "FZdRtNwH7jmADecj60ClOK69AHHnfTvvuwKLUgY0_AoC",
+      "version": "mApUsju36efRytN4WFdopPYMfYgAI8ODzTmYq3zNEqsC",
       }
     ],
     "condition": 'download_fuchsia_deps',
@@ -682,16 +682,6 @@ hooks = [
         Var('emsdk_ver')],
     'condition': 'download_emscripten'
   },
-  {
-    'name': 'Erase arch/ from fuchsia sdk',
-    'pattern': '.',
-    'action': [
-      'rm',
-      '-rf',
-      'sdk/third_party/fuchsia/sdk/linux/arch',
-    ],
-    'condition': 'download_fuchsia_deps'
-  },
   {
     'name': 'Download Fuchsia system images',
     'pattern': '.',

build/fuchsia/with_envs.py

@@ -45,6 +45,9 @@ def Main():
     os.environ['FUCHSIA_GN_SDK_ROOT'] = os.path.join(os.environ['SRC_ROOT'],
                                                      'third_party', 'fuchsia',
                                                      'gn-sdk', 'src')
+    os.environ['FUCHSIA_READELF'] = os.path.join(os.environ['SRC_ROOT'],
+                                                 'buildtools', 'linux-x64',
+                                                 'clang', 'bin', 'llvm-readelf')
 
     with subprocess.Popen(sys.argv[1:]) as proc:
         try: