ci: add missing image and enable Go module proxy in daily CI build (#1001)

* fix: add missing image property to 1ES pipeline pool config

The daily-ci-build pipeline was failing because the pool configuration
specified os: linux but was missing the required image property.
Added image: ubuntu-latest to match the os setting.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* fix: enable Go internal module proxy feature flag

After August 2025, 1ES pipelines require opting in to the internal
public module proxy for Go builds via the featureFlags parameter.
See aka.ms/goproxy for details.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: ramsessanchez

.azure-pipelines/daily-ci-build.yml

@@ -21,7 +21,12 @@ extends:
   parameters:
     pool:
       name: Azure-Pipelines-1ESPT-ExDShared
+      image: ubuntu-latest
       os: linux
+    featureFlags:
+      golang:
+        internalModuleProxy:
+          enabled: true
     sdl:
       sourceAnalysisPool:
         name: Azure-Pipelines-1ESPT-ExDShared