TUN-9800: Migrate cloudflared-ci pipelines to Gitlab CI

## Summary

This commit migrates the cloduflared ci pipelines, that built, tested and component tested the linux binaries to gitlab ci.

The only thing that is remaining to move from teamcity to gitlab are now the release pipelines that run on master.

Relates to TUN-9800

.gitlab-ci.yml

@@ -1,27 +1,13 @@
 variables:
-  # Define GOPATH within the project directory to allow GitLab CI to cache it.
-  # By default, Go places modules in GOMODCACHE, often outside the project.
-  # Explicitly setting GOMODCACHE ensures it's within the cached path.
-  GOPATH: "$CI_PROJECT_DIR/.go"
-  GOMODCACHE: "$GOPATH/pkg/mod"
-  GO_BIN_DIR: "$GOPATH/bin"
-  GO_VERSION: "go1.24.4"
-
-cache:
-  # Cache Go modules and the binaries.
-  # The 'key' ensures a unique cache per branch, or you can use a fixed key
-  # for a shared cache across all branches if that fits your workflow.
-  key: "$CI_COMMIT_REF_SLUG"
-  paths:
-    - ${GOPATH}/pkg/mod/ # For Go modules
-    - ${GO_BIN_DIR}/
+  GO_VERSION: "go1.24.6"
+  GIT_DEPTH: "0"
 
 default:
   id_tokens:
     VAULT_ID_TOKEN:
       aud: https://vault.cfdata.org
 
-stages: [pre-build, build, test, package, release]
+stages: [pre-build, build, validate, test, package, release]
 
 include:
   #####################################################
@@ -34,6 +20,11 @@ include:
   #####################################################
   - local: .ci/ci-image.gitlab-ci.yml
 
+  #####################################################
+  ################## Linux Builds ###################
+  #####################################################
+  - local: .ci/linux.gitlab-ci.yml
+
   #####################################################
   ################## Windows Builds ###################
   #####################################################
@@ -48,27 +39,3 @@ include:
   ################# Release Packages ##################
   #####################################################
   - local: .ci/release.gitlab-ci.yml
-
-# Template for Go setup, including caching and installation
-.go_setup:
-  image: docker-registry.cfdata.org/stash/devtools/ci-builders/golang-1.24/master:3219-cc8b513@sha256:4fe3ff47ba07f9b23429f49fbd063cc1a34156dd11b8113e325ad3762f94a1db
-  before_script:
-    - mkdir -p ${GOPATH} ${GOMODCACHE} ${GO_BIN_DIR}
-    - export PATH=$PATH:${GO_BIN_DIR}
-    - go env -w GOMODCACHE=${GOMODCACHE} # Ensure go uses the cached module path
-
-    # Check if govulncheck is already installed and install it if not
-    - if [ ! -f ${GO_BIN_DIR}/govulncheck ]; then
-      echo "govulncheck not found in cache, installing...";
-      go install golang.org/x/vuln/cmd/govulncheck@latest;
-      else
-      echo "govulncheck found in cache, skipping installation.";
-      fi
-
-vulncheck:
-  stage: build
-  extends: .go_setup
-  rules:
-    - !reference [.default-rules, run-on-branch]
-  script:
-    - make vulncheck