Windows: Enable proxy with fix to cert issue with Py 3.10+

Packaging reported issue that python installation
without proxy didn't work - therefore enabling proxy
back was needed but with a fix to handle Py 3.10+ changes

Py 3.10+ pip 24.2 has moved to use system certifications
by default which caused issue when proxy is used
and if host didn't have one specific certification
GlobalSign Root CA - R3 for pypi.org.

Also noticed that sometimes Windows x64 images seemed to
have this missing certification, but after installing it
to Windows ARM (which was clearly missing it) - logs showed
they didn't have it - and direct check to both Win x64
Tier1 images showed that they didn't have that cert.

Not sure what steps in provisioning or proxy usage could have
affected to that, but missing certification is now added directly
to all of these new three Windows Tier 1 images:
   - qtci-windows-10_22H2-x86_64-52 (via QTQAINFRA-6207)
   - qtci-windows-11_23H2-x86_64-53
   - qtci-windows-11_22H2-aarch64-53 (only to branches 6.8, 6.9)

Therefore --use-deprecated=legacy-certs flag is not needed
when system has correct certification available as Py 3.10+
has moved to use them by default.

Long-term improvements could still be added in future, in two ways:
   1) Internal package cache (QTQAINFRA-6485 QTQAINFRA-5531), or
   2) To update system certificates with Py 3.10+

But those will need more time to decide and implement.

Therefore this improved quick fix to get proxy back with Py 3.10+
was needed now and it removes previous quick fix to unset proxy.

Task-number: QTQAINFRA-6490
Task-number: QTQAINFRA-6473
Pick-to: 6.5 6.2
Change-Id: I0805a70cf1163012094505162d28640e9ea8e6bb
Reviewed-by: Tero Heikkinen <tero.heikkinen@qt.io>
Reviewed-by: Heikki Halmet <heikki.halmet@qt.io>
(cherry picked from commit 61c5bb072f)
(cherry picked from commit aa22a35f05)

coin/platform_configs/cmake_platforms.yaml

@@ -74,7 +74,7 @@ Configurations:
     ]
 -
     Id: 'windows-11_23H2-msvc2022'
-    Template: 'qtci-windows-11_23H2-x86_64-52'
+    Template: 'qtci-windows-11_23H2-x86_64-53'
     Compiler: 'MSVC2022'
     Features: ['Sccache', "DebugAndRelease", 'UseConfigure', 'Packaging']
     Configure arguments: '-debug-and-release -force-debug-info -headersclean -nomake examples -qt-zlib'
@@ -192,7 +192,7 @@ Configurations:
     ]
 -
     Id: 'windows-11_23H2-llvm'
-    Template: 'qtci-windows-11_23H2-x86_64-52'
+    Template: 'qtci-windows-11_23H2-x86_64-53'
     Compiler: 'Clang'
     Features: ['Packaging','Sccache', 'UseConfigure']
     Configure arguments: '-release -force-debug-info -separate-debug-info -nomake examples'
@@ -205,7 +205,7 @@ Configurations:
     ]
 -
     Id: 'windows-11_23H2-mingw11-developer-build'
-    Template: 'qtci-windows-11_23H2-x86_64-52'
+    Template: 'qtci-windows-11_23H2-x86_64-53'
     Compiler: 'Mingw'
     Features: ['Sccache', 'WarningsAreErrors', 'UseConfigure']
     Configure arguments: '-developer-build -release -force-debug-info -separate-debug-info -make examples'

coin/provisioning/common/windows/set-proxy.ps1

@@ -5,9 +5,6 @@ $n = Get-Content "$PSScriptRoot\..\shared\http_proxy.txt"
 $n = $n.Split('=')
 New-Variable -Name $n[0] -Value $n[1]
 
-Write-Host "Temporarily not setting proxy" # QTQAINFRA-6473
-$proxy = ""
-
 if ([string]::IsNullOrEmpty($proxy)) {
     Write-Host "No proxy is defined."
 } else {