TUN-9495: Remove references to cloudflare-go

## Summary
When bumping cloudflared to use go1.24, we no longer need cloudflare-go,
since most of the PQ and FIPS compliant curves are already available in go 1.24.
Therefore, we can remove everything related with installing our go toolchain.

.teamcity/install-cloudflare-go.sh

@@ -1,8 +0,0 @@
-# !/usr/bin/env bash
-
-cd /tmp
-git clone -q https://github.com/cloudflare/go
-cd go/src
-# https://github.com/cloudflare/go/tree/af19da5605ca11f85776ef7af3384a02a315a52b is version go1.22.5-devel-cf
-git checkout -q af19da5605ca11f85776ef7af3384a02a315a52b
-./make.bash

.teamcity/mac/install-cloudflare-go.sh

@@ -1,10 +0,0 @@
-rm -rf /tmp/go
-export GOCACHE=/tmp/gocache
-rm -rf $GOCACHE
-
-./.teamcity/install-cloudflare-go.sh
-
-export PATH="/tmp/go/bin:$PATH"
-go version
-which go
-go env

.teamcity/windows/install-cloudflare-go.ps1

@@ -1,16 +0,0 @@
-Set-StrictMode -Version Latest
-$ErrorActionPreference = "Stop"
-$ProgressPreference = "SilentlyContinue"
-
-Write-Output "Downloading cloudflare go..."
-
-Set-Location "$Env:Temp"
-
-git clone -q https://github.com/cloudflare/go
-Write-Output "Building go..."
-cd go/src
-# https://github.com/cloudflare/go/tree/af19da5605ca11f85776ef7af3384a02a315a52b is version go1.22.5-devel-cf
-git checkout -q af19da5605ca11f85776ef7af3384a02a315a52b
-& ./make.bat
-
-Write-Output "Installed"

.teamcity/windows/install-go-msi.ps1

@@ -1,20 +0,0 @@
-$ErrorActionPreference = "Stop"
-$ProgressPreference = "SilentlyContinue"
-$GoMsiVersion = "go1.22.5.windows-amd64.msi"
-
-Write-Output "Downloading go installer..."
-
-Set-Location "$Env:Temp"
-
-(New-Object System.Net.WebClient).DownloadFile(
-    "https://go.dev/dl/$GoMsiVersion",
-    "$Env:Temp\$GoMsiVersion"
-)
-
-Write-Output "Installing go..."
-Install-Package "$Env:Temp\$GoMsiVersion" -Force
-
-# Go installer updates global $PATH
-go env
-
-Write-Output "Installed"