[libc++][NFC] Remove a bunch of unused environment variables from the CI configs

Author: philnik777

.github/workflows/libcxx-build-and-test.yaml

@@ -33,18 +33,6 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
   cancel-in-progress: true
 
-
-env:
-  # LLVM POST-BRANCH bump version
-  # LLVM POST-BRANCH add compiler test for ToT - 1, e.g. "Clang 17"
-  # LLVM RELEASE bump remove compiler ToT - 3, e.g. "Clang 15"
-  LLVM_HEAD_VERSION: "19"   # Used compiler, update POST-BRANCH.
-  LLVM_PREVIOUS_VERSION: "18"
-  LLVM_OLDEST_VERSION: "17"
-  GCC_STABLE_VERSION: "13"
-  LLVM_SYMBOLIZER_PATH: "/usr/bin/llvm-symbolizer-19"
-  CLANG_CRASH_DIAGNOSTICS_DIR: "crash_diagnostics"
-
 jobs:
   stage1:
     if: github.repository_owner == 'llvm'

libcxx/utils/ci/buildkite-pipeline.yml

@@ -17,13 +17,6 @@
 # goal being to reduce the load on testers when a commit is known to fail.
 #
 
-env:
-    # LLVM POST-BRANCH bump version
-    # LLVM POST-BRANCH add compiler test for ToT - 1, e.g. "Clang 17"
-    # LLVM RELEASE bump remove compiler ToT - 3, e.g. "Clang 15"
-    LLVM_HEAD_VERSION: "18"   # Used compiler, update POST-BRANCH.
-    GCC_STABLE_VERSION: "13"
-
 definitions:
   _common: &common
     timeout_in_minutes: 120