Fix release CI for self-hosted runners (#4770)

## Issue Addressed

NA

## Proposed Changes

Disables some commands for self-hosted runners to prevent failures.

## Additional Info

NA

.github/workflows/release.yml

@@ -14,6 +14,8 @@ env:
     DOCKER_USERNAME: ${{ secrets.DOCKER_USERNAME }}
     REPO_NAME: ${{ github.repository_owner }}/lighthouse
     IMAGE_NAME: ${{ github.repository_owner }}/lighthouse
+    # Enable self-hosted runners for the sigp repo only.
+    SELF_HOSTED_RUNNERS: ${{ github.repository == 'sigp/lighthouse' }}
 
 jobs:
     extract-version:
@@ -68,6 +70,7 @@ jobs:
             - name: Checkout sources
               uses: actions/checkout@v3
             - name: Get latest version of stable Rust
+              if: env.SELF_HOSTED_RUNNERS == 'false'
               run: rustup update stable
 
             # ==============================
@@ -75,7 +78,7 @@ jobs:
             # ==============================
 
             - uses: KyleMayes/install-llvm-action@v1
-              if: startsWith(matrix.arch, 'x86_64-windows')
+              if: env.SELF_HOSTED_RUNNERS == 'false' && startsWith(matrix.arch, 'x86_64-windows')
               with:
                 version: "15.0"
                 directory: ${{ runner.temp }}/llvm