Remove install-tar & mentions from repo (#40720)

Author: wtgodbe

.azure/pipelines/jobs/default-build.yml

@@ -188,8 +188,6 @@ jobs:
             ./eng/scripts/InstallGoogleChrome.ps1
           displayName: Install Chrome
     - ${{ if eq(parameters.agentOs, 'Windows') }}:
-      - powershell: ./eng/scripts/InstallTar.ps1
-        displayName: Find or install Tar
       - powershell: Write-Host "##vso[task.prependpath]$(DOTNET_CLI_HOME)\.dotnet\tools"
         displayName: Add dotnet tools to path
     - ${{ if ne(parameters.agentOs, 'Windows') }}:

docs/BuildFromSource.md

@@ -109,10 +109,6 @@ NodeJS installs the Node package manager (npm) by default. This repo depends on
 npm install -g yarn
 ```
 
-#### [tar](http://gnuwin32.sourceforge.net/packages/gtar.htm) on Windows
-
-Building the repo requires tar to be installed. First, check whether `tar.exe` is already in your path i.e. execute `tar -help` (Win10 comes with tar already installed). Then, assuming you have `git` installed, you might add `C:\Program Files\Git\usr\bin\` to your path to pick up the `tar.exe` that ships with `git`. Finally, you can find installation executables of tar at <http://gnuwin32.sourceforge.net/packages/gtar.htm>; download that and add the installation directory to your PATH variable.
-
 #### Java Development Kit on Windows
 
 This repo contains some Java source code that depends on an install of the JDK v11 or newer. The JDK can be installed from either: