Refactor environment variable handling in release workflow

.github/workflows/release.yaml

@@ -32,8 +32,7 @@ jobs:
           - name: Linux aarch64
             target: aarch64-unknown-linux-musl
             build-args: "--release --features=jemalloc"
-            env:
-              JEMALLOC_SYS_WITH_LG_PAGE: "16"
+            JEMALLOC_SYS_WITH_LG_PAGE: "16"
 
           - name: Linux armv7hf
             target: armv7-unknown-linux-musleabihf
@@ -147,7 +146,8 @@ jobs:
 
       - name: Build ${{ matrix.platform.name }} binary
         uses: actions-rs/cargo@v1
-        env: ${{matrix.platform.env}}
+        env: 
+          JEMALLOC_SYS_WITH_LG_PAGE: ${{matrix.platform.JEMALLOC_SYS_WITH_LG_PAGE || "4"}}
         # We use cross-rs if not running on x86_64 architecture on Linux
         with:
           command: build