Reverts "Content aware hash moved to script and tracked (flutter#166717)" (flutter#166864)

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Reverts: flutter#166717
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Initiated by: matanlurey
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Reason for reverting: Broke tree on
[postsubmit](https://logs.chromium.org/logs/flutter/buildbucket/cr-buildbucket/8718108088961866849/+/u/test:_run_suite_safari-dart2js-canvaskit-engine/stdout)
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Original PR Author: jtmcdole
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Reviewed By: {matanlurey}
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This change reverts the following previous change:
1. Calculate the hash in only two places: `content_aware_hash.{ps1|sh}`
2. Call this from the workflow
3. Eventually call this from `update_engine_version.{ps1|sh}`

 The files of import:
* `DEPS`: tracks third party dependencies related to building the engine
* `engine`: all the code in the engine folder
* `bin/internal/content_aware_hash.ps1`: script for calculating the hash
on windows
* `bin/internal/content_aware_hash.sh`: script for calculating the hash
on mac/linux
* `.github/workflows/content-aware-hash.yml`: github action for CI/CD
hashing

Tested on windows and mac:

```shell
PS C:\src\flutter> C:\src\flutter\bin\internal\content_aware_hash.ps1
c24231e276e0719738e175e0622e040ad21a7012
```

```shell
❯ ~/src/flutter/bin/internal/content_aware_hash.sh
c24231e276e0719738e175e0622e040ad21a7012
```
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Co-authored-by: auto-submit[bot] <[email protected]>

Author: auto-submit[bot]

.github/workflows/content-aware-hash.yml

@@ -19,7 +19,7 @@ jobs:
 
       - name: Generate Hash
         run: |
-          engine_content_hash=$(bin/internal/content_aware_hash.sh)
+          engine_content_hash=$(git ls-tree HEAD DEPS bin/internal/release-candidate-branch.version engine | git hash-object --stdin)
           # test notice annotation for retrival from api
           echo "::notice ::{\"engine_content_hash\": \"${engine_content_hash}\"}"
           # test summary writing

bin/internal/content_aware_hash.ps1

@@ -2599,7 +2599,6 @@ const Set<String> kExecutableAllowlist = <String>{
   'bin/flutter-dev',
   'bin/internal/update_dart_sdk.sh',
   'bin/internal/update_engine_version.sh',
-  'bin/internal/content_aware_hash.sh',
 
   'dev/bots/codelabs_build_test.sh',
   'dev/bots/docs.sh',