Merge #18650: qt: Make bitcoin.ico non-executable

a95af77 qt: Make bitcoin.ico non-executable (practicalswift)

Pull request description:

  Make `bitcoin.ico` non-executable.

  No need to execute icons and having +x bits laying around breaks `find … -executable` :)

  Before this patch:

  ```sh
  $ find $(git ls-files -- ":(exclude)*.sh" ":(exclude)*.py") -executable
  ci/retry/retry
  contrib/macdeploy/macdeployqtplus
  depends/config.guess
  depends/config.sub
  src/qt/res/icons/bitcoin.ico
  src/secp256k1/src/modules/recovery/main_impl.h
  ```

  After this patch:

  ```sh
  $ find $(git ls-files -- ":(exclude)*.sh" ":(exclude)*.py") -executable
  ci/retry/retry
  contrib/macdeploy/macdeployqtplus
  depends/config.guess
  depends/config.sub
  src/secp256k1/src/modules/recovery/main_impl.h
  ```

  FWIW:

  ```
  $ file $(find $(git ls-files -- ":(exclude)*.sh" ":(exclude)*.py") -executable)
  ci/retry/retry:                                 Bourne-Again shell script, UTF-8 Unicode text executable
  contrib/macdeploy/macdeployqtplus:              Python script, ASCII text executable
  depends/config.guess:                           POSIX shell script, ASCII text executable
  depends/config.sub:                             POSIX shell script, ASCII text executable
  src/qt/res/icons/bitcoin.ico:                   MS Windows icon resource - 10 icons, 48x48, 16 colors, 4 bits/pixel, 32x32, 16 colors, 4 bits/pixel
  src/secp256k1/src/modules/recovery/main_impl.h: C source, ASCII text
  ```

ACKs for top commit:
  MarcoFalke:
    ACK a95af77 gitian build finished, so it doesn't look like the icon used in Windows resource files needs to be executable. Though, I didn't read the documentation.
  jonatack:
    ACK a95af77

Tree-SHA512: ecf9154077824ae4c274b4341e985797f3648c0cb0c31cb25ce382163b923a3acbc7048683720be4ae3663501801129cd0f48c441a36f049cc304ebe9f30994e

Author: MarcoFalke