Revert "Temporarily allow the TSan (free-threading) job to fail (#152173)"

This reverts commit 4f39efc.

Author: kumaraditya303

.github/workflows/build.yml

@@ -554,6 +554,7 @@ jobs:
         - Thread
         free-threading:
         - false
+        - true
         sanitizer:
         - TSan
         include:
@@ -565,17 +566,6 @@ jobs:
       sanitizer: ${{ matrix.sanitizer }}
       free-threading: ${{ matrix.free-threading }}
 
-  # XXX: Temporarily allow this job to fail to not block PRs.
-  build-san-free-threading:
-    # ${{ '' } is a hack to nest jobs under the same sidebar category.
-    name: Sanitizers${{ '' }}  # zizmor: ignore[obfuscation]
-    needs: build-context
-    if: needs.build-context.outputs.run-ubuntu == 'true'
-    uses: ./.github/workflows/reusable-san.yml
-    with:
-      sanitizer: TSan
-      free-threading: true
-
   cross-build-linux:
     name: Cross build Linux
     runs-on: ubuntu-26.04
@@ -679,7 +669,6 @@ jobs:
     - test-hypothesis
     - build-asan
     - build-san
-    - build-san-free-threading
     - cross-build-linux
     - cifuzz
     if: always()
@@ -691,7 +680,6 @@ jobs:
         allowed-failures: >-
           build-android,
           build-emscripten,
-          build-san-free-threading,
           build-windows-msi,
           build-ubuntu-ssltests,
           test-hypothesis,